1
00:00:04,400 --> 00:00:07,760
Speaker 1: Welcome to text Stuff, a production from my Heart Radio.

2
00:00:12,160 --> 00:00:14,960
Speaker 1: Hey there, and welcome to tech Stuff. I'm your host,

3
00:00:15,120 --> 00:00:18,560
Speaker 1: Jonathan Strickland. I'm an executive producer with I Heart Radio,

4
00:00:18,680 --> 00:00:22,360
Speaker 1: and I love all things tech. And here's a really

5
00:00:22,400 --> 00:00:28,680
Speaker 1: cool thing about technology. Technology is the proof that science works.

6
00:00:29,160 --> 00:00:31,360
Speaker 1: So you can think of technology is sort of the

7
00:00:31,400 --> 00:00:35,800
Speaker 1: physical manifestation of our understanding of science. And as we

8
00:00:35,920 --> 00:00:39,120
Speaker 1: learn more about how our universe works, we can build

9
00:00:39,159 --> 00:00:43,040
Speaker 1: stuff that leverages what we've learned. We can even leverage

10
00:00:43,040 --> 00:00:47,040
Speaker 1: how the universe works without having a full understanding of

11
00:00:47,040 --> 00:00:50,960
Speaker 1: the scientific principles. Though in general, the better we understand

12
00:00:50,960 --> 00:00:54,680
Speaker 1: those principles, the better technology we can make. And one

13
00:00:54,760 --> 00:00:58,360
Speaker 1: subset of technology that I think really illustrates this well

14
00:00:59,040 --> 00:01:02,560
Speaker 1: is musical instrument and so in this episode and in

15
00:01:02,600 --> 00:01:05,920
Speaker 1: the next episode, I'll talk about the science behind music

16
00:01:06,000 --> 00:01:09,720
Speaker 1: without getting too deep into musical theory that's its own thing,

17
00:01:10,400 --> 00:01:14,880
Speaker 1: and how musical instruments are an example of physics and action. Now,

18
00:01:14,959 --> 00:01:18,640
Speaker 1: in the past, I've done episodes on stuff like synthesizers

19
00:01:18,680 --> 00:01:22,200
Speaker 1: and electric guitars and pickups and amplifiers, you know, describing

20
00:01:22,240 --> 00:01:26,880
Speaker 1: how electronics gave musicians new ways to make sounds, including

21
00:01:26,880 --> 00:01:30,280
Speaker 1: sounds that have never been created before. But honestly, the

22
00:01:30,480 --> 00:01:34,360
Speaker 1: entire history of musical instruments kind of follows that path.

23
00:01:34,959 --> 00:01:37,759
Speaker 1: It's just that some of those instruments are the kind

24
00:01:37,800 --> 00:01:40,600
Speaker 1: that you plug in or that you connect to amplifiers

25
00:01:40,680 --> 00:01:44,280
Speaker 1: or whatever, and some aren't. But they all relate back

26
00:01:44,319 --> 00:01:47,920
Speaker 1: to science in some way or another. Music marries the

27
00:01:48,000 --> 00:01:51,520
Speaker 1: scientific with the creative, and it's one of the manifestations

28
00:01:51,520 --> 00:01:54,920
Speaker 1: of ingenuity that I really love. Case in point, the

29
00:01:55,000 --> 00:01:58,280
Speaker 1: inspiration for today's episode came out of something I was

30
00:01:58,520 --> 00:02:02,840
Speaker 1: genuinely curious about out myself. See, I'm not a musician

31
00:02:03,040 --> 00:02:06,280
Speaker 1: by any stretch of the imagination. Though I do own

32
00:02:06,440 --> 00:02:10,280
Speaker 1: a few musical instruments, I was never in band or

33
00:02:10,400 --> 00:02:13,760
Speaker 1: orchestra or anything like that. So I was sitting there thinking,

34
00:02:14,520 --> 00:02:17,600
Speaker 1: how the heck does a trumpet work? And I researched it,

35
00:02:17,639 --> 00:02:19,280
Speaker 1: and then I thought, you know, I should do a

36
00:02:19,320 --> 00:02:22,560
Speaker 1: tech stuff episode on this. But then I kept going

37
00:02:22,560 --> 00:02:25,120
Speaker 1: down the rabbit hole and decided to do something a

38
00:02:25,200 --> 00:02:28,400
Speaker 1: little more ambitious than how a trumpet works. So in

39
00:02:28,440 --> 00:02:32,239
Speaker 1: today's episode, I'm going to talk more generally about music

40
00:02:32,280 --> 00:02:36,040
Speaker 1: instruments and how they work. By explaining the physics behind

41
00:02:36,320 --> 00:02:38,920
Speaker 1: the art of music, because when you get down to it,

42
00:02:39,160 --> 00:02:42,040
Speaker 1: a musical instrument is really just taking what we understand

43
00:02:42,040 --> 00:02:45,760
Speaker 1: about physics, building a real world object based on that understanding,

44
00:02:45,880 --> 00:02:48,160
Speaker 1: and then putting it to use to make something beautiful

45
00:02:48,520 --> 00:02:53,600
Speaker 1: or interesting, or, in my case, terrible. To understand all this,

46
00:02:53,880 --> 00:02:57,240
Speaker 1: it's best to start with a scientific breakdown of the

47
00:02:57,280 --> 00:03:02,520
Speaker 1: phenomenon of sound. And there's an old philosophical question that says,

48
00:03:02,880 --> 00:03:05,960
Speaker 1: if a tree falls in the forest and nobody is

49
00:03:06,000 --> 00:03:09,200
Speaker 1: around to hear it, does it make a sound? Now,

50
00:03:09,280 --> 00:03:12,680
Speaker 1: one point of this question could be to say, if

51
00:03:12,720 --> 00:03:16,240
Speaker 1: there's no way to observe something happening, can we really

52
00:03:16,280 --> 00:03:20,720
Speaker 1: be sure that it actually happened, particularly something as ephemeral

53
00:03:20,760 --> 00:03:23,440
Speaker 1: as sound, So if no one was there to observe it,

54
00:03:23,520 --> 00:03:28,200
Speaker 1: can we say for sure that something observable happened. But

55
00:03:28,280 --> 00:03:30,600
Speaker 1: another way that we could look at the same question

56
00:03:30,800 --> 00:03:33,919
Speaker 1: is to say, is sound really a thing if there

57
00:03:34,040 --> 00:03:36,480
Speaker 1: is no one there to perceive it? Because sound is

58
00:03:36,520 --> 00:03:41,440
Speaker 1: really describing how our brains process incoming fluctuations of air pressure.

59
00:03:42,000 --> 00:03:45,520
Speaker 1: In this case, we're not necessarily asking if the vibrations

60
00:03:45,560 --> 00:03:49,000
Speaker 1: from the tree happened or not. It's more that if

61
00:03:49,000 --> 00:03:52,880
Speaker 1: there is no one to experience that as sound, would

62
00:03:52,920 --> 00:03:56,280
Speaker 1: we really say that a sound happened? Is the experience

63
00:03:56,360 --> 00:04:00,280
Speaker 1: necessary to call it sound? Now I don't have an

64
00:04:00,280 --> 00:04:02,440
Speaker 1: answer to that question, but I do want to talk

65
00:04:02,480 --> 00:04:06,240
Speaker 1: more about what's going on with sounds. So at the

66
00:04:06,320 --> 00:04:10,720
Speaker 1: very heart of it, sound comes from vibrations. Generally, when

67
00:04:10,720 --> 00:04:13,640
Speaker 1: we talk about sound, we typically mean it comes from

68
00:04:14,080 --> 00:04:18,080
Speaker 1: vibrations of air molecules, which gets to that fluctuation and

69
00:04:18,160 --> 00:04:21,240
Speaker 1: air pressure that I was talking about. It's fluctuations and

70
00:04:21,279 --> 00:04:25,840
Speaker 1: air pressure that ultimately are sound most of the time

71
00:04:25,880 --> 00:04:28,440
Speaker 1: when we're talking about it. Sound can actually travel through

72
00:04:28,680 --> 00:04:32,360
Speaker 1: really any physical medium. It's just that it travels more

73
00:04:32,360 --> 00:04:35,280
Speaker 1: easily through some rather than others. And the way we

74
00:04:35,720 --> 00:04:38,880
Speaker 1: usually encounter it is through the air. So let's say

75
00:04:38,920 --> 00:04:42,280
Speaker 1: for a moment that you have the incredible superpower to

76
00:04:42,520 --> 00:04:45,640
Speaker 1: zoom and enhance your vision, and you can also see

77
00:04:45,800 --> 00:04:49,279
Speaker 1: air molecules, so you're actually looking at the air molecules

78
00:04:49,320 --> 00:04:52,520
Speaker 1: all around you. Now, imagine that you see someone clap

79
00:04:52,600 --> 00:04:55,800
Speaker 1: their hands, and as they clap their hands, they're causing

80
00:04:55,839 --> 00:04:59,440
Speaker 1: a bunch of air molecules to bounce around into each other,

81
00:04:59,680 --> 00:05:02,560
Speaker 1: and that creates a chain reaction that passes from the

82
00:05:02,600 --> 00:05:07,000
Speaker 1: point of origin, that being the clapping hands outward like

83
00:05:07,040 --> 00:05:09,840
Speaker 1: a ripple and a pond, almost but in all directions.

84
00:05:10,160 --> 00:05:13,080
Speaker 1: Now you're paying really close attention, and you notice that

85
00:05:13,160 --> 00:05:16,919
Speaker 1: as the collisions move outward, the reaction as a whole

86
00:05:17,200 --> 00:05:20,159
Speaker 1: begins to appear to lose energy. So the further you

87
00:05:20,240 --> 00:05:23,040
Speaker 1: out from the point of origin, the less you'll see

88
00:05:23,040 --> 00:05:26,279
Speaker 1: those air molecules move, and eventually you'll be far enough

89
00:05:26,279 --> 00:05:29,400
Speaker 1: out where the movement is imperceptible. And this is why

90
00:05:29,440 --> 00:05:32,640
Speaker 1: sounds are louder when you're closer to the point of origin,

91
00:05:32,880 --> 00:05:36,120
Speaker 1: which I admit is about as basic an idea as

92
00:05:36,160 --> 00:05:39,680
Speaker 1: I can communicate. But the reason those sounds are softer

93
00:05:39,800 --> 00:05:43,280
Speaker 1: when you're further away, assuming you don't have some interesting

94
00:05:43,320 --> 00:05:48,320
Speaker 1: curvature of the acoustic area around you, the reason that

95
00:05:48,440 --> 00:05:51,320
Speaker 1: they're softer is that the energy of that initial vibration

96
00:05:51,520 --> 00:05:54,760
Speaker 1: gets diluted as the reaction passes outward. And you can

97
00:05:54,800 --> 00:05:57,760
Speaker 1: think of it as the origin of the sound affects

98
00:05:57,800 --> 00:06:00,400
Speaker 1: a relatively small number of air molecules and at least

99
00:06:00,400 --> 00:06:03,599
Speaker 1: surrounding that point of origin, and it causes those air

100
00:06:03,600 --> 00:06:07,680
Speaker 1: molecules to fluctuate. Those fluctuating air molecules cause a larger

101
00:06:07,760 --> 00:06:12,120
Speaker 1: number of surrounding air molecules to fluctuate. But because you're

102
00:06:12,120 --> 00:06:16,160
Speaker 1: talking about transferring energy from a smaller number of molecules

103
00:06:16,200 --> 00:06:19,480
Speaker 1: to a larger number of molecules, the amount of energy

104
00:06:19,560 --> 00:06:23,520
Speaker 1: transmitted to that second group of air molecules means that

105
00:06:23,600 --> 00:06:26,920
Speaker 1: each individual molecule is getting less than the first group.

106
00:06:27,440 --> 00:06:30,120
Speaker 1: You know, energy cannot be created or destroyed, so we're

107
00:06:30,120 --> 00:06:33,200
Speaker 1: not getting rid of energy here, it's just we're spreading

108
00:06:33,200 --> 00:06:37,480
Speaker 1: it out across a larger area, so each individual component

109
00:06:38,000 --> 00:06:41,360
Speaker 1: is getting slightly less energy than the previous group. Now,

110
00:06:41,400 --> 00:06:43,760
Speaker 1: of course, in the real world it's not quite so

111
00:06:43,960 --> 00:06:47,400
Speaker 1: neat and simple as saying a circle of air molecules

112
00:06:47,600 --> 00:06:50,880
Speaker 1: than affects and slightly larger circle that affects a slightly

113
00:06:51,000 --> 00:06:54,120
Speaker 1: larger circle, and so on. But you get the idea.

114
00:06:54,320 --> 00:06:58,000
Speaker 1: When we talk about vibrations, we mentioned stuff like frequency,

115
00:06:58,320 --> 00:07:00,760
Speaker 1: and that word is all about the number of times

116
00:07:00,800 --> 00:07:04,400
Speaker 1: a repeating event occurs within a given unit of time.

117
00:07:04,839 --> 00:07:07,880
Speaker 1: So with sound, we usually refer to frequency in terms

118
00:07:07,920 --> 00:07:12,040
Speaker 1: of units called hurts, h, E, R, t z. This

119
00:07:12,120 --> 00:07:15,680
Speaker 1: tells us how many times this particular repeated event, and

120
00:07:15,840 --> 00:07:20,840
Speaker 1: oscillation happens within the span of a second. Twenty hurts,

121
00:07:20,960 --> 00:07:23,520
Speaker 1: which is generally said to be the lower end of

122
00:07:23,560 --> 00:07:27,360
Speaker 1: the typical range for human hearing, would be a wave

123
00:07:27,400 --> 00:07:32,480
Speaker 1: that's oscillating twenty times per second. Any vibration slower than

124
00:07:32,520 --> 00:07:34,560
Speaker 1: that would be at such a low frequency that the

125
00:07:34,600 --> 00:07:37,880
Speaker 1: average person would be unable to hear it. A twenty

126
00:07:38,000 --> 00:07:41,280
Speaker 1: killer hurts sound, which is at the tippy top end

127
00:07:41,400 --> 00:07:45,240
Speaker 1: of typical human hearing, would mean that the oscillating wave

128
00:07:45,480 --> 00:07:49,200
Speaker 1: is oscillating at a speed of twenty thousand times per second.

129
00:07:49,800 --> 00:07:52,440
Speaker 1: So that means if you had a string that vibrated

130
00:07:52,480 --> 00:07:55,120
Speaker 1: at twenty hurts, you can set up a high speed

131
00:07:55,160 --> 00:07:58,760
Speaker 1: camera on that string, and when you pluck the string

132
00:07:59,280 --> 00:08:01,800
Speaker 1: and you're use that high speed camera to shoot video

133
00:08:01,840 --> 00:08:04,640
Speaker 1: of it, you would see that for every second in

134
00:08:04,720 --> 00:08:07,600
Speaker 1: real time that passes, you could count the string making

135
00:08:07,640 --> 00:08:11,560
Speaker 1: twenty full cycles, which means going up and down past

136
00:08:11,640 --> 00:08:14,280
Speaker 1: the camera that's one full cycle. Not just passing it once,

137
00:08:14,280 --> 00:08:18,600
Speaker 1: it has to pass it twice. That would be twenty hurts. Now,

138
00:08:18,760 --> 00:08:22,440
Speaker 1: we also tend to talk about sound waves, and this

139
00:08:22,480 --> 00:08:24,960
Speaker 1: gets a little complicated because we can mean different things

140
00:08:25,040 --> 00:08:27,160
Speaker 1: by sound waves. We could be talking about the actual

141
00:08:27,320 --> 00:08:32,000
Speaker 1: physical wave of air fluctuations that propagates outwards from the

142
00:08:32,080 --> 00:08:34,440
Speaker 1: origin of sound, or we could be talking about a

143
00:08:34,559 --> 00:08:40,319
Speaker 1: visualization of the qualities of a sound. And this gets

144
00:08:40,320 --> 00:08:42,920
Speaker 1: into a territory where it's tricky to explain this without

145
00:08:43,040 --> 00:08:45,320
Speaker 1: visual aids, but we're gonna try. So we're gonna talk

146
00:08:45,360 --> 00:08:48,520
Speaker 1: about the visualization without visual aids. So I want you

147
00:08:48,559 --> 00:08:51,480
Speaker 1: to imagine that you have a piece of paper, and

148
00:08:51,760 --> 00:08:54,040
Speaker 1: across the middle of this piece of paper, you draw

149
00:08:54,080 --> 00:08:57,480
Speaker 1: a straight horizontal line from left to right goes all

150
00:08:57,480 --> 00:09:00,520
Speaker 1: the way across the paper. And this law line in

151
00:09:00,559 --> 00:09:03,959
Speaker 1: this particular representation is going to represent time. This is

152
00:09:04,000 --> 00:09:07,520
Speaker 1: the X axis. So the left side of your paper,

153
00:09:08,080 --> 00:09:11,520
Speaker 1: where you're starting point is, represents zero seconds. The far

154
00:09:11,720 --> 00:09:15,480
Speaker 1: right sign represents some arbitrary point of time. We'll get

155
00:09:15,520 --> 00:09:17,600
Speaker 1: to that in a second, because it all depends on

156
00:09:17,679 --> 00:09:21,000
Speaker 1: the specific kind of wave you're drawing. So now let's

157
00:09:21,000 --> 00:09:26,000
Speaker 1: just imagine drawing a nice sign wave, and we start

158
00:09:26,040 --> 00:09:30,079
Speaker 1: on the leftmost side at the center point, so zero

159
00:09:30,160 --> 00:09:33,560
Speaker 1: at the center horizontal line, and draw a nice gentle

160
00:09:33,760 --> 00:09:37,560
Speaker 1: crest up and then we come back down cross that

161
00:09:37,720 --> 00:09:42,559
Speaker 1: center line and then draw an equally gentle trough that

162
00:09:42,720 --> 00:09:46,280
Speaker 1: is of equivalent size to the crest on the opposite side.

163
00:09:46,760 --> 00:09:50,360
Speaker 1: And then once the line comes back up and crosses

164
00:09:50,360 --> 00:09:54,440
Speaker 1: the horizontal line again, we've got one wavelength of a

165
00:09:54,480 --> 00:09:57,560
Speaker 1: sound wave that this would be in what we would

166
00:09:57,600 --> 00:10:00,880
Speaker 1: call the time domain. The reason we call it the

167
00:10:00,920 --> 00:10:04,160
Speaker 1: time domain is that we are visualizing a sound wave

168
00:10:04,600 --> 00:10:08,880
Speaker 1: with regard to the passing of time. That X axis

169
00:10:08,920 --> 00:10:12,600
Speaker 1: again is showing the time is passing. So the wavelength

170
00:10:12,640 --> 00:10:16,480
Speaker 1: describes the distance or the amount of time that passes

171
00:10:16,520 --> 00:10:21,360
Speaker 1: between two corresponding points on a sign wave. So let's

172
00:10:21,360 --> 00:10:23,280
Speaker 1: say we draw a series of these like we get

173
00:10:23,320 --> 00:10:28,240
Speaker 1: twenty sheets of paper, and we draw equal sign waves

174
00:10:28,280 --> 00:10:30,120
Speaker 1: on each of those twenty sheets of paper, and we

175
00:10:30,160 --> 00:10:31,800
Speaker 1: put them all side by side, so we get a

176
00:10:31,880 --> 00:10:36,199
Speaker 1: nice continuous wave all the way down these twenty sheets wide.

177
00:10:36,960 --> 00:10:41,960
Speaker 1: And we say that each sheet represents one twentieth of

178
00:10:42,000 --> 00:10:44,319
Speaker 1: a second, so that when we have twenty of them

179
00:10:44,360 --> 00:10:47,880
Speaker 1: side by side, that represents one seconds worth of time.

180
00:10:48,320 --> 00:10:51,840
Speaker 1: You would say I have twenty wave lengths that span

181
00:10:52,000 --> 00:10:57,400
Speaker 1: one second. That means that this represents twenty hurts. This

182
00:10:57,480 --> 00:11:00,240
Speaker 1: is a sound wave with a frequency of twenty Hurts

183
00:11:00,280 --> 00:11:04,520
Speaker 1: because it takes twenty of these will pass a given

184
00:11:04,600 --> 00:11:08,840
Speaker 1: point in space within the span of one second. So

185
00:11:08,880 --> 00:11:12,360
Speaker 1: then we need to talk about the period of a wave,

186
00:11:12,679 --> 00:11:16,200
Speaker 1: and this is the inverse of Frequency is the amount

187
00:11:16,200 --> 00:11:20,000
Speaker 1: of time it takes for one wavelength to complete one cycle.

188
00:11:20,720 --> 00:11:23,920
Speaker 1: So frequency is the number of cycles per second. The

189
00:11:24,000 --> 00:11:27,280
Speaker 1: period of a wave is the number of seconds per cycle.

190
00:11:27,600 --> 00:11:32,000
Speaker 1: So for a twenty Hurts frequency, the period of the

191
00:11:32,040 --> 00:11:35,800
Speaker 1: wave would be one seconds per cycle. That's why we

192
00:11:35,800 --> 00:11:39,400
Speaker 1: would need twenty sheets of paper with just one nice

193
00:11:39,480 --> 00:11:44,400
Speaker 1: curvy wave on each piece to represent a twenty Hurts wave.

194
00:11:44,520 --> 00:11:46,640
Speaker 1: Now you could just do this on one sheet of paper,

195
00:11:46,880 --> 00:11:49,360
Speaker 1: you know, you just change the scale. So you change

196
00:11:49,360 --> 00:11:53,720
Speaker 1: the scale so that every single wavelength represents of a second.

197
00:11:54,280 --> 00:11:56,640
Speaker 1: You draw twenty of those on one sheet of paper.

198
00:11:56,800 --> 00:11:59,559
Speaker 1: Will be much smaller than our original example, but that

199
00:11:59,559 --> 00:12:01,640
Speaker 1: would still will be a twenty Hurts wave. It's all

200
00:12:01,760 --> 00:12:06,480
Speaker 1: dependent on the scale of your representation. Wavelength and frequency

201
00:12:06,520 --> 00:12:10,320
Speaker 1: are related, and we see that in an equation where

202
00:12:10,360 --> 00:12:16,680
Speaker 1: we say velocity equals wavelength times frequency. So velocity describes

203
00:12:16,720 --> 00:12:19,560
Speaker 1: the speed and direction. But we can ignore that for

204
00:12:19,640 --> 00:12:23,040
Speaker 1: now of a wave as it passes a stationary point.

205
00:12:23,400 --> 00:12:26,240
Speaker 1: So if we know two of those three factors, we

206
00:12:26,280 --> 00:12:28,480
Speaker 1: can figure out the third. But just a little math, right,

207
00:12:28,640 --> 00:12:31,280
Speaker 1: If we know the velocity and we know the wavelength, well,

208
00:12:31,520 --> 00:12:33,760
Speaker 1: we can divide the velocity by the wavelength and then

209
00:12:33,760 --> 00:12:36,360
Speaker 1: we have the frequency. Or if we know the frequency

210
00:12:36,400 --> 00:12:39,040
Speaker 1: but not the wavelength, we can divide the velocity by

211
00:12:39,080 --> 00:12:41,640
Speaker 1: the frequency. We get the wavelength. If we know the

212
00:12:41,679 --> 00:12:43,800
Speaker 1: frequency and the wavelength, we multiply them together, we get

213
00:12:43,800 --> 00:12:50,679
Speaker 1: the velocity. Pretty easy stuff. Now, speed of sound is

214
00:12:51,200 --> 00:12:53,200
Speaker 1: not that difficult for us to to get our minds

215
00:12:53,240 --> 00:12:55,800
Speaker 1: wrapped around, because we know what the speed of sound

216
00:12:55,960 --> 00:13:00,120
Speaker 1: is generally speaking, so the speed of sound depends partly

217
00:13:00,320 --> 00:13:03,600
Speaker 1: upon the medium through which the sound is traveling. Sound

218
00:13:03,679 --> 00:13:06,400
Speaker 1: moves at different speeds through water than it does through

219
00:13:06,400 --> 00:13:09,240
Speaker 1: the air, for example. But even in the air, stuff

220
00:13:09,400 --> 00:13:12,160
Speaker 1: can affect the speed of sound, like the air's humidity

221
00:13:12,240 --> 00:13:15,880
Speaker 1: and its temperature. Essentially, we're talking about density. The density

222
00:13:15,920 --> 00:13:18,559
Speaker 1: of those air molecules will affect how quickly sound can

223
00:13:18,559 --> 00:13:21,560
Speaker 1: travel through it. So when we talk about the speed

224
00:13:21,559 --> 00:13:24,640
Speaker 1: of sound, we have to get more specific. So we

225
00:13:24,760 --> 00:13:27,880
Speaker 1: tend to describe the speed of sound as being three

226
00:13:27,960 --> 00:13:31,520
Speaker 1: hundred forty three meters per second in dry air at

227
00:13:31,559 --> 00:13:35,120
Speaker 1: twenty degrees celsius. Now, for my fellow Americans out there

228
00:13:35,120 --> 00:13:37,480
Speaker 1: who ain't got time to truck with no sensible metrics

229
00:13:37,480 --> 00:13:40,840
Speaker 1: system or celsius or anything, this would mean sound travels

230
00:13:40,840 --> 00:13:44,160
Speaker 1: at about one thousand, one twenty five ft per second

231
00:13:44,320 --> 00:13:48,240
Speaker 1: when the air is sixty eight degrees fahrenheit. Sound at

232
00:13:48,280 --> 00:13:52,720
Speaker 1: all frequencies will travel at the same speed through any

233
00:13:52,840 --> 00:13:56,319
Speaker 1: given medium. So that means that a low pitch sound

234
00:13:56,600 --> 00:13:59,400
Speaker 1: and a high pitch sound will both cover the same

235
00:13:59,440 --> 00:14:02,280
Speaker 1: amount of space in the same amount of time through

236
00:14:02,360 --> 00:14:06,600
Speaker 1: the same medium. But low sounds have low frequencies and

237
00:14:06,640 --> 00:14:10,839
Speaker 1: thus longer wavelengths than high sounds, which are higher frequencies

238
00:14:11,000 --> 00:14:13,840
Speaker 1: with shorter wavelengths. It will take the same amount of

239
00:14:13,840 --> 00:14:16,160
Speaker 1: time for a high pitch note on a trumpet to

240
00:14:16,280 --> 00:14:18,880
Speaker 1: get to you as a low blast note on a

241
00:14:18,920 --> 00:14:22,360
Speaker 1: tuba that's played at the same distance, but the high

242
00:14:22,400 --> 00:14:24,640
Speaker 1: pitched note will have a higher frequency and a shorter

243
00:14:24,720 --> 00:14:27,760
Speaker 1: wavelength than the tubus note. Now I've used this analogy

244
00:14:27,800 --> 00:14:30,520
Speaker 1: several times before, but imagine that you've got a two

245
00:14:30,680 --> 00:14:34,160
Speaker 1: lane highway and you've got a line of buses that

246
00:14:34,200 --> 00:14:36,680
Speaker 1: are in the right lane, and the buses are one

247
00:14:36,760 --> 00:14:39,600
Speaker 1: right after the other. And in the left lane you've

248
00:14:39,600 --> 00:14:43,280
Speaker 1: got a line of compact cars. And for every bus,

249
00:14:43,440 --> 00:14:46,640
Speaker 1: you can fit three cars in that same length of space.

250
00:14:47,400 --> 00:14:49,640
Speaker 1: And the front of the first car is in line

251
00:14:49,640 --> 00:14:52,320
Speaker 1: with the front of the first bus. The rear bumper

252
00:14:52,320 --> 00:14:54,480
Speaker 1: of the last car lines up with the rear bumper

253
00:14:54,520 --> 00:14:57,840
Speaker 1: of the last bus. Both lanes of traffic are traveling

254
00:14:57,920 --> 00:15:01,920
Speaker 1: at the exact same speed. Down highway, both lanes of

255
00:15:01,960 --> 00:15:06,040
Speaker 1: traffic will cross a finish line at the exact same time. However,

256
00:15:06,520 --> 00:15:09,200
Speaker 1: you have more cars in lane two than you have

257
00:15:09,320 --> 00:15:12,560
Speaker 1: buses in lane one. Everyone's going at the same speed.

258
00:15:12,840 --> 00:15:14,640
Speaker 1: That's kind of the way we have to think about

259
00:15:14,760 --> 00:15:18,600
Speaker 1: sound waves and frequencies. If a sound is low enough,

260
00:15:18,880 --> 00:15:20,760
Speaker 1: we may not hear it at all, But if it

261
00:15:20,840 --> 00:15:22,880
Speaker 1: is a strong enough signal, meaning it has a great

262
00:15:22,880 --> 00:15:26,480
Speaker 1: deal of amplitude, we could physically feel it. You remember,

263
00:15:26,520 --> 00:15:31,000
Speaker 1: it's air fluctuations, it's actual air pressure. So typically we

264
00:15:31,040 --> 00:15:34,320
Speaker 1: would perceive amplitude as volume, and in our sketch of

265
00:15:34,320 --> 00:15:36,320
Speaker 1: a wave, it would mean that the peaks and low

266
00:15:36,360 --> 00:15:39,440
Speaker 1: points would be really far out from that center line,

267
00:15:39,520 --> 00:15:42,080
Speaker 1: you know, the taller those peaks are, the greater the

268
00:15:42,160 --> 00:15:45,600
Speaker 1: amplitude or greater the volume. If you've ever been near

269
00:15:45,680 --> 00:15:49,240
Speaker 1: a massive sub whiffer and you felt pressure, like in

270
00:15:49,280 --> 00:15:53,120
Speaker 1: your chest, but you couldn't really hear anything, chances are

271
00:15:53,120 --> 00:15:56,280
Speaker 1: it means the sub whoffer was blasting out vibrations below

272
00:15:56,320 --> 00:15:59,840
Speaker 1: your threshold of hearing. Typically, when we talk about music,

273
00:16:00,160 --> 00:16:03,480
Speaker 1: we talk a lot more about frequencies than we do

274
00:16:03,560 --> 00:16:07,720
Speaker 1: about wavelength and that's because of this relationship between frequency

275
00:16:07,800 --> 00:16:11,160
Speaker 1: and pitch. But wavelengths are also important as they will

276
00:16:11,200 --> 00:16:14,480
Speaker 1: become a key component of stuff like resonance and harmonics

277
00:16:14,520 --> 00:16:18,400
Speaker 1: and boyality. Let me tell you, preparing this section of

278
00:16:18,440 --> 00:16:20,680
Speaker 1: the podcast was a heck of a thing all by itself,

279
00:16:20,760 --> 00:16:23,960
Speaker 1: because this is stuff that's way easier to explain with

280
00:16:24,040 --> 00:16:26,320
Speaker 1: visual aids. But stick with me because I know you

281
00:16:26,320 --> 00:16:28,600
Speaker 1: guys are smart enough to suss it all out, so

282
00:16:28,640 --> 00:16:30,840
Speaker 1: it really just falls on me to describe it clearly.

283
00:16:31,360 --> 00:16:34,320
Speaker 1: So another thing we need to understand before we jump

284
00:16:34,360 --> 00:16:36,120
Speaker 1: into that, and we'll take a break before we get

285
00:16:36,160 --> 00:16:38,200
Speaker 1: to resonance and harmonics. But one other thing I want

286
00:16:38,240 --> 00:16:41,840
Speaker 1: to explain is the phase of a wave. A wave's

287
00:16:42,000 --> 00:16:46,239
Speaker 1: phase refers to how it is offset from some specific

288
00:16:46,280 --> 00:16:49,440
Speaker 1: starting position. And it really becomes important when you're talking

289
00:16:49,440 --> 00:16:53,480
Speaker 1: about multiple waves. Because multiple waves can be offset from

290
00:16:53,520 --> 00:16:56,080
Speaker 1: one another. They can be out of phase with each other,

291
00:16:56,400 --> 00:16:59,920
Speaker 1: and that affects the sounds that we perceive. So, going

292
00:17:00,000 --> 00:17:03,160
Speaker 1: back to our original sketch of a single wave, imagine

293
00:17:03,160 --> 00:17:06,359
Speaker 1: that you draw a new wave using that same series

294
00:17:06,400 --> 00:17:09,080
Speaker 1: of pieces of paper, but you use a different color

295
00:17:09,359 --> 00:17:11,840
Speaker 1: for this new wave, and you offset it a bit.

296
00:17:12,000 --> 00:17:13,960
Speaker 1: So instead of starting at the far left of the

297
00:17:14,000 --> 00:17:17,479
Speaker 1: first sheet, let's say you start one inch in so

298
00:17:17,520 --> 00:17:20,159
Speaker 1: it's offset from that first wave. Otherwise it follows the

299
00:17:20,160 --> 00:17:23,600
Speaker 1: exact same trajectory. Well, these two waves would be out

300
00:17:23,640 --> 00:17:27,080
Speaker 1: of phase with respect of each other. Why is this

301
00:17:27,160 --> 00:17:30,640
Speaker 1: all important? I'll explain in a second, but first let's

302
00:17:30,640 --> 00:17:41,000
Speaker 1: take a quick break. Okay, So before the break, I

303
00:17:41,080 --> 00:17:44,240
Speaker 1: talked about the phase of a sound wave. Imagine you've

304
00:17:44,240 --> 00:17:47,520
Speaker 1: got two of the same frequency of sound, but they're

305
00:17:47,520 --> 00:17:50,000
Speaker 1: out of phase with each other. That would affect how

306
00:17:50,040 --> 00:17:53,560
Speaker 1: we perceived the sound. It could get pretty noisy. Actually.

307
00:17:53,960 --> 00:17:57,640
Speaker 1: If the two frequencies, however, are perfectly opposite each other,

308
00:17:58,000 --> 00:18:01,479
Speaker 1: so that the crests in sound wave a match up

309
00:18:01,520 --> 00:18:05,360
Speaker 1: perfectly with the troughs of sound wave B, and they're

310
00:18:05,400 --> 00:18:09,040
Speaker 1: of the exact same frequency and amplitude, we wouldn't hear

311
00:18:09,119 --> 00:18:12,160
Speaker 1: the sound at all because those two sound waves would

312
00:18:12,160 --> 00:18:14,560
Speaker 1: cancel each other out. You can think of it in

313
00:18:14,600 --> 00:18:18,000
Speaker 1: this way. Think of air molecule number one is pushing

314
00:18:18,000 --> 00:18:20,920
Speaker 1: to the right on air molecule number two, but air

315
00:18:21,000 --> 00:18:24,600
Speaker 1: molecule two is pushing just as hard on the left

316
00:18:24,680 --> 00:18:27,960
Speaker 1: to air molecule number one, which means neither air molecule

317
00:18:27,960 --> 00:18:31,880
Speaker 1: will actually move. This is how noise canceling headphones work.

318
00:18:31,920 --> 00:18:35,200
Speaker 1: By the way, the headphones incorporate a microphone. It picks

319
00:18:35,280 --> 00:18:38,800
Speaker 1: up the ambient sounds in your environment, and then speakers

320
00:18:38,840 --> 00:18:42,160
Speaker 1: in the headphones generate the equal but opposite sound waves

321
00:18:42,200 --> 00:18:44,360
Speaker 1: to cancel out the ones that you would otherwise hear

322
00:18:44,880 --> 00:18:48,040
Speaker 1: as long as the latency that being the lag between

323
00:18:48,119 --> 00:18:51,719
Speaker 1: detecting a sound and generating the opposite sound, As long

324
00:18:51,760 --> 00:18:53,800
Speaker 1: as that latency is low enough, we humans are too

325
00:18:53,880 --> 00:18:55,880
Speaker 1: slow to pick up on the difference, and our perception

326
00:18:55,960 --> 00:18:58,399
Speaker 1: is really limited in that way. But the out of

327
00:18:58,440 --> 00:19:00,680
Speaker 1: face stuff also matters a lot when we talk about

328
00:19:00,680 --> 00:19:05,160
Speaker 1: things like resonance and harmonics as well. So I guess

329
00:19:05,240 --> 00:19:07,720
Speaker 1: there's no time like the present to finally get into

330
00:19:07,760 --> 00:19:11,000
Speaker 1: all that stuff. It is incredibly important with musical instruments,

331
00:19:11,040 --> 00:19:14,000
Speaker 1: So the descriptions I've used so far really refer to

332
00:19:14,160 --> 00:19:17,240
Speaker 1: pure pitches, which is something we can generate with electronics,

333
00:19:17,320 --> 00:19:20,040
Speaker 1: but it's not typically what we get with musical instruments

334
00:19:20,040 --> 00:19:24,000
Speaker 1: outside of things like tuning forks. A pure pitch describes

335
00:19:24,119 --> 00:19:28,119
Speaker 1: a single frequency with no harmonics or overtones, so we

336
00:19:28,200 --> 00:19:31,320
Speaker 1: don't get any other frequencies other than the base one,

337
00:19:31,400 --> 00:19:35,040
Speaker 1: the fundamental frequency. We're getting a pure tone, which we

338
00:19:35,080 --> 00:19:38,439
Speaker 1: could plot as a smooth, consistent sign wave with equal

339
00:19:38,480 --> 00:19:41,359
Speaker 1: crests and troughs, nice and neat, kind of like the

340
00:19:41,400 --> 00:19:43,680
Speaker 1: example I was describing at the top of this episode.

341
00:19:44,000 --> 00:19:47,159
Speaker 1: But in the real world, the sounds we hear typically

342
00:19:47,200 --> 00:19:51,080
Speaker 1: consist of more than one frequency. There are multiple frequencies

343
00:19:51,119 --> 00:19:54,360
Speaker 1: going on here. We can still plot the sound waves,

344
00:19:54,560 --> 00:19:57,359
Speaker 1: but they wouldn't look like those nice, smooth curves we

345
00:19:57,359 --> 00:20:01,200
Speaker 1: were talking about earlier. They would be funk looking potentially,

346
00:20:01,200 --> 00:20:04,680
Speaker 1: with little dips and bumps and the crests and troughs.

347
00:20:04,720 --> 00:20:08,280
Speaker 1: And that's because we'd be representing a collection of frequencies

348
00:20:08,560 --> 00:20:12,000
Speaker 1: in a single way. Visualization sort of the visual equivalent

349
00:20:12,040 --> 00:20:15,040
Speaker 1: of how we would perceive the sound through hearing. So

350
00:20:15,160 --> 00:20:18,080
Speaker 1: let's go through with an example. Let's say you're strumming

351
00:20:18,080 --> 00:20:21,080
Speaker 1: a guitar string, and that string will vibrate and not

352
00:20:21,200 --> 00:20:24,840
Speaker 1: just one frequency, but a few different frequencies all at

353
00:20:24,840 --> 00:20:28,960
Speaker 1: the same time. All of these frequencies are resonant frequencies,

354
00:20:29,160 --> 00:20:32,520
Speaker 1: meaning these are the collection of vibration speeds at which

355
00:20:32,600 --> 00:20:37,919
Speaker 1: that string naturally experiences when it is strummed. However, human

356
00:20:37,920 --> 00:20:40,600
Speaker 1: hearing is such that we typically only hear the pitch

357
00:20:40,760 --> 00:20:44,399
Speaker 1: of the lowest resonant frequency in that bunch. This is

358
00:20:44,400 --> 00:20:47,760
Speaker 1: the fundamental frequency. You can think of it as the baseline.

359
00:20:48,280 --> 00:20:52,960
Speaker 1: In musical instruments. The additional resonant frequencies those higher than

360
00:20:53,000 --> 00:20:57,760
Speaker 1: the fundamental frequency, higher in frequency, so more hurts. In

361
00:20:57,800 --> 00:21:02,479
Speaker 1: other words, are typically, but not exclusively, harmonics of the

362
00:21:02,520 --> 00:21:07,159
Speaker 1: fundamental and a harmonic is a whole number multiple of

363
00:21:07,200 --> 00:21:10,760
Speaker 1: the fundamental frequency. So let's focus on that guitar string.

364
00:21:10,760 --> 00:21:13,120
Speaker 1: It's a lot easier if we talk about a specific example.

365
00:21:14,000 --> 00:21:17,879
Speaker 1: So we're gonna say that we're gonna play the A string.

366
00:21:18,240 --> 00:21:20,720
Speaker 1: Why the A string, Well, because it has a fundamental

367
00:21:20,720 --> 00:21:24,320
Speaker 1: frequency of one ten hurts. It makes it very easy

368
00:21:24,359 --> 00:21:27,760
Speaker 1: for us to do multiples. So the fundamental frequency sees

369
00:21:27,800 --> 00:21:30,760
Speaker 1: the string vibrate one hundred ten times per second. That

370
00:21:30,760 --> 00:21:33,760
Speaker 1: means a full sequence of going up and down and

371
00:21:33,800 --> 00:21:37,760
Speaker 1: returning to starting point on times per second. The string

372
00:21:37,840 --> 00:21:40,320
Speaker 1: is anchored at either end of the guitar. If we

373
00:21:40,359 --> 00:21:42,320
Speaker 1: could slow down time, we would see that length of

374
00:21:42,359 --> 00:21:45,679
Speaker 1: string making that up down journey one ten times every second.

375
00:21:45,840 --> 00:21:49,919
Speaker 1: But the string is also vibrating at other frequencies that

376
00:21:50,000 --> 00:21:53,440
Speaker 1: are higher than the fundamental In general, we call these

377
00:21:53,480 --> 00:21:59,080
Speaker 1: overtones together. The overtones with the fundamental frequency are called partials.

378
00:21:59,520 --> 00:22:02,040
Speaker 1: Now I'm going to focus on harmonics first because they

379
00:22:02,080 --> 00:22:05,040
Speaker 1: are the easiest to grasp. So we've got our a

380
00:22:05,119 --> 00:22:08,560
Speaker 1: string with a hundred ten hurts frequency. That's our fundamental

381
00:22:08,600 --> 00:22:12,400
Speaker 1: tone or first harmonic. The next harmonic would be twice

382
00:22:12,520 --> 00:22:15,960
Speaker 1: the frequency as two is the next whole number. It's

383
00:22:15,960 --> 00:22:19,200
Speaker 1: the next integer in the sequence. We start with one,

384
00:22:19,440 --> 00:22:22,280
Speaker 1: but any number of times one is itself. We go

385
00:22:22,320 --> 00:22:25,600
Speaker 1: to the next integer, that's two. So now we multiply

386
00:22:26,080 --> 00:22:31,600
Speaker 1: our frequency hurts by two, we get two hurts. That's

387
00:22:31,600 --> 00:22:33,879
Speaker 1: still an A. It's still the note A, but it's

388
00:22:33,880 --> 00:22:37,399
Speaker 1: an octave higher than the original a note that we played.

389
00:22:37,920 --> 00:22:41,000
Speaker 1: So hypothetically, this also means if you've got a string

390
00:22:41,400 --> 00:22:45,480
Speaker 1: that's tuned to one hurts and you shortened the length

391
00:22:45,520 --> 00:22:48,200
Speaker 1: of that string by half, so you made it half

392
00:22:48,240 --> 00:22:51,560
Speaker 1: as long, you would produce the two D twenty Hurts

393
00:22:51,600 --> 00:22:54,760
Speaker 1: tone when you strummed the half as long string. You

394
00:22:54,880 --> 00:22:58,240
Speaker 1: shortened the wavelength by shortening the string. Thus you increase

395
00:22:58,280 --> 00:23:03,440
Speaker 1: the frequency because remember we remember velocity is wavelength times frequency.

396
00:23:03,520 --> 00:23:07,000
Speaker 1: Velocity is constant, so if we have the wavelength, we

397
00:23:07,040 --> 00:23:10,000
Speaker 1: have to double the frequency. At least that's what would

398
00:23:10,000 --> 00:23:12,840
Speaker 1: happen in an ideal realization of this principle, But in

399
00:23:12,920 --> 00:23:16,800
Speaker 1: reality it gets more complicated because the oscillating wave in

400
00:23:16,840 --> 00:23:20,680
Speaker 1: a guitar string doesn't propagate all the way from one

401
00:23:20,720 --> 00:23:22,679
Speaker 1: anchored end of the string all the way to the

402
00:23:22,680 --> 00:23:25,719
Speaker 1: other end of this string. Instead, there's actually a small

403
00:23:25,840 --> 00:23:28,679
Speaker 1: length of string that's close to the anchor points that

404
00:23:28,800 --> 00:23:32,240
Speaker 1: doesn't move. It's something that people tend to call the

405
00:23:32,400 --> 00:23:36,120
Speaker 1: dead length of string. Now, the amount of dead length,

406
00:23:36,200 --> 00:23:39,320
Speaker 1: like the length of that non moving part of the string,

407
00:23:39,680 --> 00:23:42,000
Speaker 1: depends on a lot of factors, like how thick the

408
00:23:42,040 --> 00:23:44,919
Speaker 1: string is, so there's no hard and fast rule of

409
00:23:44,920 --> 00:23:47,479
Speaker 1: how long the dead length will be. In general, this

410
00:23:47,560 --> 00:23:50,879
Speaker 1: actually means that the actual halfway mark down a string

411
00:23:51,000 --> 00:23:54,880
Speaker 1: doesn't necessarily correspond to doubling the vibrational frequency of that string.

412
00:23:55,600 --> 00:23:57,880
Speaker 1: But we'll get more into that in the next episode,

413
00:23:58,280 --> 00:24:00,320
Speaker 1: I hope. So we're gonna put it aside for now.

414
00:24:00,400 --> 00:24:04,200
Speaker 1: That's a future Jonathan problem. So the next harmonic would

415
00:24:04,200 --> 00:24:08,080
Speaker 1: be three times the fundamental right, we just did two hurts,

416
00:24:08,160 --> 00:24:12,639
Speaker 1: so three would be that's right, three thirty hurts, which

417
00:24:12,760 --> 00:24:15,440
Speaker 1: we would perceive as an E note if we could

418
00:24:15,440 --> 00:24:19,080
Speaker 1: hear it over the fundamental frequency, and so on. We

419
00:24:19,080 --> 00:24:21,719
Speaker 1: would go up the harmonic scale. The fourth harmonic at

420
00:24:21,760 --> 00:24:23,600
Speaker 1: four or forty would get us back to another A

421
00:24:23,720 --> 00:24:27,520
Speaker 1: note at a higher octave uh five fifty For the

422
00:24:27,600 --> 00:24:31,080
Speaker 1: fifth harmonic would actually be close to a C sharp,

423
00:24:31,280 --> 00:24:33,480
Speaker 1: but not exactly C sharp. It would be a little

424
00:24:33,520 --> 00:24:38,400
Speaker 1: off by just a few hurts. Now, overtones aren't necessarily

425
00:24:38,440 --> 00:24:43,200
Speaker 1: at harmonic frequencies. We tend to design musical instruments that

426
00:24:43,280 --> 00:24:46,840
Speaker 1: produce harmonics as overtones because we find them more pleasing

427
00:24:46,880 --> 00:24:51,600
Speaker 1: to the ear. Typically, but different instruments will produce different overtones.

428
00:24:52,040 --> 00:24:57,080
Speaker 1: At different intensities, So some might really emphasize the third

429
00:24:57,400 --> 00:25:01,879
Speaker 1: partial or third harmonic, others m really emphasize the fifth harmonic.

430
00:25:02,560 --> 00:25:05,040
Speaker 1: And this is why we can hear the same note

431
00:25:05,160 --> 00:25:08,600
Speaker 1: played on two different types of musical instruments, and we

432
00:25:08,640 --> 00:25:14,320
Speaker 1: experienced two different qualities of sound, two different experiences of sound.

433
00:25:14,800 --> 00:25:18,640
Speaker 1: So a G played on a banjo sounds different from

434
00:25:18,680 --> 00:25:21,639
Speaker 1: that same G note played on a guitar, and that

435
00:25:21,680 --> 00:25:24,000
Speaker 1: sounds different from that same G note played on a

436
00:25:24,040 --> 00:25:27,520
Speaker 1: piano or a G on a trumpet. Each of these

437
00:25:27,560 --> 00:25:32,280
Speaker 1: instruments produces overtones of varying degrees of intensity. And while

438
00:25:32,280 --> 00:25:36,400
Speaker 1: we don't necessarily perceive the pitch of those overtones, we don't,

439
00:25:36,600 --> 00:25:42,639
Speaker 1: you know, distinguish those other pitches. The overtones shape the sound,

440
00:25:43,040 --> 00:25:46,320
Speaker 1: It affects the timbre of the note. So we can

441
00:25:46,359 --> 00:25:48,760
Speaker 1: tell the G on a banjo and the G on

442
00:25:48,800 --> 00:25:51,960
Speaker 1: a guitar are the same pitch, they're the same note,

443
00:25:52,200 --> 00:25:54,680
Speaker 1: but they don't have the same quality of sound. If

444
00:25:54,680 --> 00:25:57,639
Speaker 1: they did, there'd be no reason to make different musical

445
00:25:57,680 --> 00:26:00,880
Speaker 1: instruments because they would all just produce the exact same sounds.

446
00:26:01,440 --> 00:26:05,040
Speaker 1: There's something else I need to say about resonance and

447
00:26:05,080 --> 00:26:08,399
Speaker 1: it involves adding energy into a system. One way to

448
00:26:08,440 --> 00:26:11,160
Speaker 1: think about this is with a swing set, So you know,

449
00:26:11,440 --> 00:26:14,120
Speaker 1: and you're a kid, or if you're me an adult

450
00:26:14,400 --> 00:26:16,800
Speaker 1: and you're swinging on a swing set, if someone gives

451
00:26:16,800 --> 00:26:18,560
Speaker 1: you a push just as you were about to start

452
00:26:18,560 --> 00:26:20,919
Speaker 1: your downward swing, you go a little higher on your

453
00:26:20,960 --> 00:26:24,960
Speaker 1: next swing because that push was adding to the natural

454
00:26:25,000 --> 00:26:29,000
Speaker 1: frequency of your swing. You're adding energy into the system.

455
00:26:29,080 --> 00:26:33,840
Speaker 1: So objects will resonate at certain frequencies, and if you

456
00:26:34,000 --> 00:26:37,800
Speaker 1: add energy at the regular intervals of that frequency, it

457
00:26:38,000 --> 00:26:42,160
Speaker 1: boosts the amplification. You get more volume, you get more energy,

458
00:26:42,600 --> 00:26:44,840
Speaker 1: And it depends on a load of factors, such as

459
00:26:44,960 --> 00:26:47,520
Speaker 1: what the physical stuff is made up of, how much

460
00:26:47,560 --> 00:26:50,159
Speaker 1: of it there is, the tension that's on it, and

461
00:26:50,240 --> 00:26:52,640
Speaker 1: lots of other stuff. But resonance is going to play

462
00:26:52,640 --> 00:26:56,040
Speaker 1: an important part in how some specific instruments work. So

463
00:26:56,080 --> 00:26:59,120
Speaker 1: if a musician subjects an instrument at a resonant frequency

464
00:26:59,119 --> 00:27:02,320
Speaker 1: in some way, the sound creative and the instrument will

465
00:27:02,320 --> 00:27:06,040
Speaker 1: be a louder one. The classic example of resonance is

466
00:27:06,119 --> 00:27:11,280
Speaker 1: using a crystal champagne glasses fundamental frequency to shatter the glass,

467
00:27:11,480 --> 00:27:13,560
Speaker 1: and it's a neat trick, so The first thing you

468
00:27:13,600 --> 00:27:16,919
Speaker 1: gotta do is determine what the glass is fundamental frequency is.

469
00:27:17,520 --> 00:27:20,359
Speaker 1: Typically you do that by tapping it lightly, and you

470
00:27:20,359 --> 00:27:22,800
Speaker 1: would listen to the tone it produces, and you would

471
00:27:22,800 --> 00:27:27,000
Speaker 1: analyze that tone. Then you would subject the glass to

472
00:27:27,119 --> 00:27:30,520
Speaker 1: that same frequency of sound. The glass will begin to

473
00:27:30,600 --> 00:27:34,520
Speaker 1: vibrate in the presence of that fundamental frequency all by itself,

474
00:27:35,080 --> 00:27:37,040
Speaker 1: so you don't have to strike it or anything. It's

475
00:27:37,080 --> 00:27:39,840
Speaker 1: as if the glass has been struck. It will resonate

476
00:27:40,400 --> 00:27:43,639
Speaker 1: along with that frequency. It will also do this, by

477
00:27:43,680 --> 00:27:45,840
Speaker 1: the way, if you're doing one of the harmonics of

478
00:27:45,880 --> 00:27:49,320
Speaker 1: that frequency, but at a lesser degree. So if the

479
00:27:49,400 --> 00:27:52,879
Speaker 1: incoming frequency is strong enough, it will cause the glass

480
00:27:52,920 --> 00:27:55,720
Speaker 1: to vibrate to the point that deforms enough to shatter.

481
00:27:56,320 --> 00:27:57,959
Speaker 1: And there are a lot of stories of opera singers

482
00:27:58,000 --> 00:28:01,480
Speaker 1: who had perfect pitch who could managed this. They would

483
00:28:01,520 --> 00:28:04,240
Speaker 1: listen to the tone and replicate it perfectly, and with

484
00:28:04,400 --> 00:28:07,760
Speaker 1: their training, they would produce in a volume loud enough

485
00:28:07,800 --> 00:28:10,000
Speaker 1: to shatter the glass. These days, it's a lot easier

486
00:28:10,000 --> 00:28:12,480
Speaker 1: to do this because you just use a digital device

487
00:28:12,560 --> 00:28:15,840
Speaker 1: capable of dialing into a precise frequency, and then you

488
00:28:15,880 --> 00:28:18,359
Speaker 1: pump that frequency out to some speakers that can blast

489
00:28:18,400 --> 00:28:21,040
Speaker 1: out the sound at a sufficient volume and the glass

490
00:28:21,080 --> 00:28:24,399
Speaker 1: will just shatter itself. But uh, we're not done with

491
00:28:24,400 --> 00:28:26,800
Speaker 1: the hard stuff yet. Now we have to talk about

492
00:28:26,840 --> 00:28:31,480
Speaker 1: Furrier transforms. And who knew that music was so darn complicated?

493
00:28:32,040 --> 00:28:34,159
Speaker 1: I mean, Bach did, but you know you get what

494
00:28:34,200 --> 00:28:37,720
Speaker 1: I mean. Back in the eighteenth and early nineteenth centuries,

495
00:28:37,760 --> 00:28:42,080
Speaker 1: we had this smarty pants named Jean Baptiste Joseph Fourier,

496
00:28:42,760 --> 00:28:45,960
Speaker 1: or Old Joe as i'll call him. So. Old Joe

497
00:28:46,120 --> 00:28:48,800
Speaker 1: was a physicist and a mathematician born way back in

498
00:28:48,840 --> 00:28:51,920
Speaker 1: seventeen sixty eight, and he was really interested in explaining

499
00:28:51,920 --> 00:28:55,680
Speaker 1: the flow of heat between adjacent molecules. But his work

500
00:28:55,880 --> 00:28:58,800
Speaker 1: would lay the foundation for other smarty pants assess is

501
00:28:59,120 --> 00:29:01,520
Speaker 1: to build upon net, leading to what we would call

502
00:29:01,560 --> 00:29:06,680
Speaker 1: the Furrier transform. Not many people called the Furrier transform,

503
00:29:06,800 --> 00:29:09,640
Speaker 1: so I'll just say Furrier. But what the heck does

504
00:29:09,680 --> 00:29:12,600
Speaker 1: this have to do with music? Well, remember when I

505
00:29:12,640 --> 00:29:15,240
Speaker 1: said if you wanted to depict a true sound wave

506
00:29:15,320 --> 00:29:17,920
Speaker 1: as a type of sign wave, it would look really

507
00:29:17,960 --> 00:29:20,480
Speaker 1: funky because the presence of all those overtones, it would

508
00:29:20,480 --> 00:29:23,880
Speaker 1: make all these different dips and peaks, and it would

509
00:29:23,920 --> 00:29:26,360
Speaker 1: just look very odd. It wouldn't be those smooth curves

510
00:29:26,360 --> 00:29:29,600
Speaker 1: we were talking about originally, Well, we humans wouldn't hear

511
00:29:29,640 --> 00:29:33,320
Speaker 1: all those frequencies as distinct pitches, but a meter could

512
00:29:33,440 --> 00:29:37,040
Speaker 1: pick up all those different frequencies together. Basically, the Furrier

513
00:29:37,080 --> 00:29:41,760
Speaker 1: transform describes how these multiple frequencies all combine into that

514
00:29:42,000 --> 00:29:45,240
Speaker 1: one wave, which in our sketch means it creates that

515
00:29:45,320 --> 00:29:48,760
Speaker 1: single wave visualization that incorporates all the frequencies at their

516
00:29:48,800 --> 00:29:53,120
Speaker 1: respective amplitudes into a single, unbroken visualization of a wave.

517
00:29:53,880 --> 00:29:57,800
Speaker 1: Furier showed that a continuous function could be produced as

518
00:29:57,800 --> 00:30:01,400
Speaker 1: an infinite sum of sign and cost sign waves. The

519
00:30:01,440 --> 00:30:05,320
Speaker 1: resulting plot of the function as a wave isn't necessarily smooth,

520
00:30:05,680 --> 00:30:07,479
Speaker 1: and the shape of it will depend upon a lot

521
00:30:07,520 --> 00:30:11,440
Speaker 1: of factors, including the phase of each constituent wave, the frequency,

522
00:30:11,560 --> 00:30:13,960
Speaker 1: the amplitude, all that kind of stuff. But Furry and

523
00:30:13,960 --> 00:30:17,280
Speaker 1: those who followed him described how this collection of individual

524
00:30:17,320 --> 00:30:21,880
Speaker 1: components combine to make a whole. This applies in lots

525
00:30:21,920 --> 00:30:24,760
Speaker 1: of areas of physics, not just in sound, and in

526
00:30:24,800 --> 00:30:27,640
Speaker 1: fact we can visualize sound waves in a different way.

527
00:30:28,120 --> 00:30:31,560
Speaker 1: There's more helpful when we try to understand this. So

528
00:30:31,600 --> 00:30:35,040
Speaker 1: we've used the time domain method. Right, we've been using

529
00:30:35,040 --> 00:30:40,000
Speaker 1: that in order to describe the the wavelength and frequency

530
00:30:40,040 --> 00:30:43,320
Speaker 1: because those are really easy to visualize in terms of

531
00:30:43,320 --> 00:30:47,720
Speaker 1: of span of time. However, it gets confusing when we

532
00:30:47,720 --> 00:30:50,400
Speaker 1: want to talk about overtones and the shape of the

533
00:30:50,440 --> 00:30:53,320
Speaker 1: wave goes all funky. So we can do this by

534
00:30:53,520 --> 00:30:56,840
Speaker 1: looking at it not by the time domain but by

535
00:30:56,880 --> 00:31:01,200
Speaker 1: the frequency domain. So in the time domain, that horizontal

536
00:31:01,240 --> 00:31:04,120
Speaker 1: line or x axis relates to the passing of time,

537
00:31:04,320 --> 00:31:07,440
Speaker 1: but in the frequency domain, the x axis refers to

538
00:31:07,520 --> 00:31:11,560
Speaker 1: the range of frequencies, lower frequencies being on the left side,

539
00:31:11,760 --> 00:31:14,520
Speaker 1: higher frequencies being on the right side. So you would

540
00:31:14,560 --> 00:31:20,240
Speaker 1: plot where the frequency is on each of those overtones,

541
00:31:20,360 --> 00:31:25,320
Speaker 1: and the fundamental frequency uh and the y axis is

542
00:31:25,360 --> 00:31:29,440
Speaker 1: still amplitude, so it's still volume. So you would have

543
00:31:29,560 --> 00:31:33,280
Speaker 1: the loudest frequency, which would be the fundamental, plotted at

544
00:31:33,280 --> 00:31:35,560
Speaker 1: the highest point on the y axis, and then you

545
00:31:35,560 --> 00:31:39,360
Speaker 1: would see the overtone frequencies at their respective places, and

546
00:31:39,400 --> 00:31:42,880
Speaker 1: you would see, if you were to analyze through Furrier

547
00:31:42,960 --> 00:31:48,120
Speaker 1: analysis each musical instrument, that those overtones are slightly different

548
00:31:48,560 --> 00:31:52,200
Speaker 1: between things like guitars and banjos and harps and pianos

549
00:31:52,240 --> 00:31:56,000
Speaker 1: and flutes and trumpets, etcetera. Uh, and other things like

550
00:31:56,000 --> 00:31:58,240
Speaker 1: like whether or not you were plucking a string versus

551
00:31:58,280 --> 00:32:01,960
Speaker 1: bowing a string. All of these factor into it. Now

552
00:32:02,320 --> 00:32:04,680
Speaker 1: I get that all of this is really confusing without

553
00:32:04,720 --> 00:32:07,600
Speaker 1: visual aids, So I do recommend checking this stuff out

554
00:32:07,720 --> 00:32:09,520
Speaker 1: on the internet to get a better grasp of it.

555
00:32:09,680 --> 00:32:12,320
Speaker 1: There are numerous websites and videos on the matter, and

556
00:32:12,360 --> 00:32:14,840
Speaker 1: one really helpful one relating to what I was just

557
00:32:14,880 --> 00:32:18,920
Speaker 1: talking about is on Mark Newman's YouTube channel. It's titled

558
00:32:19,040 --> 00:32:23,200
Speaker 1: Preview how the Furrier transform works Lecture number two Sound

559
00:32:23,320 --> 00:32:26,280
Speaker 1: as sign Waves. Check that out. It will really help

560
00:32:26,320 --> 00:32:28,560
Speaker 1: clear things up. But when we get back, I'm gonna

561
00:32:28,560 --> 00:32:31,520
Speaker 1: wrap up the physics bit. Then we're gonna talk about

562
00:32:31,560 --> 00:32:42,720
Speaker 1: some biology. But first let's take a quick break. So

563
00:32:43,320 --> 00:32:47,240
Speaker 1: Furrier analysis, where we can determine the amplitudes of individual

564
00:32:47,280 --> 00:32:50,760
Speaker 1: overtones and harmonics and a played note, gives us the

565
00:32:50,880 --> 00:32:54,080
Speaker 1: scientific explanation of why the same note played across different

566
00:32:54,080 --> 00:32:57,880
Speaker 1: instruments produces a different kind of sound. The collection of

567
00:32:57,880 --> 00:33:01,120
Speaker 1: those overtones is different for every instrument. But how about

568
00:33:01,160 --> 00:33:05,160
Speaker 1: how we actually hear and perceive sound? What is the

569
00:33:05,200 --> 00:33:09,080
Speaker 1: science behind our experience of sound? Well, we'll start with

570
00:33:09,120 --> 00:33:12,920
Speaker 1: the physics and those moving air molecules what go into

571
00:33:12,960 --> 00:33:15,400
Speaker 1: our ears. So we're really talking, like I said about

572
00:33:15,440 --> 00:33:18,720
Speaker 1: fluctuating air pressure. Here, those changes in air pressure hit

573
00:33:18,720 --> 00:33:22,560
Speaker 1: our ears and they pass into the external auditory canal,

574
00:33:22,840 --> 00:33:26,040
Speaker 1: so that's open to the outside world on the inside

575
00:33:26,320 --> 00:33:30,200
Speaker 1: in our heads. It ends with the tympanic membrane, also

576
00:33:30,240 --> 00:33:32,560
Speaker 1: known as the ear drum. So this is a very

577
00:33:32,600 --> 00:33:35,160
Speaker 1: thin membrane and it's at where we would say the

578
00:33:35,240 --> 00:33:39,239
Speaker 1: outer ear begins to transition to the middle ear. On

579
00:33:39,280 --> 00:33:42,880
Speaker 1: the other side, the inner side of the tympanic membrane

580
00:33:43,400 --> 00:33:47,200
Speaker 1: is a series of three tiny bones. There, the malleus,

581
00:33:47,560 --> 00:33:50,560
Speaker 1: the incas, and the statepies or the hammer, the anvil

582
00:33:50,680 --> 00:33:53,880
Speaker 1: and the stirrup, so called because of their shape, and

583
00:33:53,960 --> 00:33:57,680
Speaker 1: as the membrane moves due to these fluctuations of air pressure,

584
00:33:57,800 --> 00:34:01,880
Speaker 1: as it's being pushed and pulled upon, the bones also move,

585
00:34:02,280 --> 00:34:05,560
Speaker 1: So the hammer pushes impoles on the anvil, which pushes

586
00:34:05,640 --> 00:34:09,200
Speaker 1: impolls on the stirrup. The stapes or stirrup connects to

587
00:34:09,239 --> 00:34:12,319
Speaker 1: the oval window. That's a section that's part of the

588
00:34:12,320 --> 00:34:16,399
Speaker 1: cochlea that's an organ in the inner ear. The cochlea

589
00:34:16,560 --> 00:34:20,040
Speaker 1: is a spiral shaped organ and there are three parallel

590
00:34:20,200 --> 00:34:25,000
Speaker 1: chambers filled with fluid inside the cochlea. The vibrations on

591
00:34:25,040 --> 00:34:28,760
Speaker 1: the oval window cause waves to flow through this fluid.

592
00:34:29,680 --> 00:34:33,920
Speaker 1: This in turn causes another membrane called the basilar membrane

593
00:34:34,040 --> 00:34:37,239
Speaker 1: to move. And it's the basilar membrane or basil or

594
00:34:37,320 --> 00:34:40,560
Speaker 1: if you prefer, that gives us the ability to differentiate

595
00:34:40,640 --> 00:34:44,520
Speaker 1: the pitches that we hear. Different sections of this membrane

596
00:34:44,760 --> 00:34:49,840
Speaker 1: respond more readily to certain frequencies of sound. Then you

597
00:34:49,880 --> 00:34:52,640
Speaker 1: have the organ of core time, which is the receptor

598
00:34:52,760 --> 00:34:56,160
Speaker 1: organ of the ear, and it detects the vibrations of

599
00:34:56,360 --> 00:35:00,439
Speaker 1: this basilar membrane through special cells, and the special cells

600
00:35:00,440 --> 00:35:03,680
Speaker 1: have little hair like protrusions on them. It acts kind

601
00:35:03,680 --> 00:35:06,800
Speaker 1: of like a brush that just rests against this membrane.

602
00:35:07,040 --> 00:35:09,719
Speaker 1: So as the membrane vibrates, the hair cells pick it up,

603
00:35:10,239 --> 00:35:13,879
Speaker 1: and then they pass along the message to the brain

604
00:35:13,920 --> 00:35:18,040
Speaker 1: through neurotransmitters, and it gets super complicated from there. But

605
00:35:18,080 --> 00:35:21,719
Speaker 1: I figured this is deep enough already. At the end,

606
00:35:21,800 --> 00:35:25,279
Speaker 1: our brains taken these incoming signals and then interpret it

607
00:35:25,320 --> 00:35:29,880
Speaker 1: and we experience it as sound. Now you can also

608
00:35:29,960 --> 00:35:34,759
Speaker 1: transmit vibrations to the tympanic membrane through stuff like bone conduction.

609
00:35:35,280 --> 00:35:38,120
Speaker 1: That's where the vibration passes, not through air molecules that

610
00:35:38,160 --> 00:35:41,120
Speaker 1: are going through the ear canal, but rather through the

611
00:35:41,160 --> 00:35:44,400
Speaker 1: bones of the skull itself. So just remember that again,

612
00:35:44,480 --> 00:35:47,600
Speaker 1: sound is one way we experience vibration, but not the

613
00:35:47,640 --> 00:35:50,040
Speaker 1: only way. I mean, obviously, if a vibration is strong enough,

614
00:35:50,040 --> 00:35:53,080
Speaker 1: we're gonna feel it. And some vibrations occurrent frequencies that

615
00:35:53,400 --> 00:35:55,160
Speaker 1: again are too high or too low for us to

616
00:35:55,200 --> 00:35:58,560
Speaker 1: perceive through sound through hearing it, but we might be

617
00:35:58,560 --> 00:36:01,920
Speaker 1: able to feel it. So the basilar membrane won't vibrate

618
00:36:02,120 --> 00:36:05,560
Speaker 1: at frequencies that are above or below the human range

619
00:36:05,560 --> 00:36:09,040
Speaker 1: of hearing, or an individual's range of human hearing, because

620
00:36:09,280 --> 00:36:12,640
Speaker 1: when we say twenty to twenty killer hurts, we're really

621
00:36:12,680 --> 00:36:15,959
Speaker 1: talking about the range of the typical human. Some people

622
00:36:16,000 --> 00:36:21,520
Speaker 1: are atypical. So you could say if a tree falls

623
00:36:22,000 --> 00:36:24,799
Speaker 1: and the vibrations that cause were above or below the

624
00:36:24,880 --> 00:36:29,440
Speaker 1: level of perception, it doesn't make a sound because sound

625
00:36:29,480 --> 00:36:33,920
Speaker 1: is dependent upon us experiencing it. You could also argue

626
00:36:33,960 --> 00:36:35,839
Speaker 1: the opposite. It all just depends on your way you're

627
00:36:35,880 --> 00:36:38,960
Speaker 1: defining things. So when a musician strums a string on

628
00:36:39,000 --> 00:36:42,200
Speaker 1: a guitar, that string vibrates, it causes the air molecules

629
00:36:42,200 --> 00:36:45,160
Speaker 1: around the string to move. Thus you get a fluctuation

630
00:36:45,200 --> 00:36:48,840
Speaker 1: of air pressure that matches that vibrating frequency. This spreads

631
00:36:48,840 --> 00:36:52,480
Speaker 1: outward from the source and the air molecules all around vibrate,

632
00:36:52,560 --> 00:36:55,600
Speaker 1: and if you're close enough, if you're within hearing distance,

633
00:36:56,080 --> 00:37:00,160
Speaker 1: that fluctuation will be strong enough to move your tympanic membrane,

634
00:37:00,560 --> 00:37:04,360
Speaker 1: which then is going to through the bones put pressure

635
00:37:04,400 --> 00:37:07,360
Speaker 1: on that oval window of your cochlea, which in turn

636
00:37:07,400 --> 00:37:10,880
Speaker 1: will cause the basilar membrane to vibrate at the particular

637
00:37:11,360 --> 00:37:14,960
Speaker 1: area on the membrane that corresponds to that frequency. The

638
00:37:15,000 --> 00:37:17,720
Speaker 1: hair cells will pick up that vibration and then emit

639
00:37:17,800 --> 00:37:21,600
Speaker 1: neurotransmitters that our brains then say, oh, I recognize that

640
00:37:21,600 --> 00:37:24,720
Speaker 1: that's in agata da vida boom. We've just heard some music.

641
00:37:25,320 --> 00:37:28,200
Speaker 1: So when you get down to it, musical instruments are

642
00:37:28,239 --> 00:37:33,120
Speaker 1: all about creating vibrations at specific frequencies. Music itself is

643
00:37:33,120 --> 00:37:37,279
Speaker 1: all about establishing rules which can occasionally be broken for

644
00:37:37,360 --> 00:37:41,280
Speaker 1: the arrangement of those frequencies in ways to achieve various effects.

645
00:37:41,760 --> 00:37:45,200
Speaker 1: Those rules aren't just about which frequencies play well with others.

646
00:37:45,360 --> 00:37:48,560
Speaker 1: It's also about stuff like amplitude. Levels of volume are

647
00:37:48,600 --> 00:37:52,440
Speaker 1: really important and play into a song's dynamic range. Dynamic

648
00:37:52,520 --> 00:37:55,719
Speaker 1: range explains the difference between the loudest versus the softest

649
00:37:55,760 --> 00:37:58,759
Speaker 1: parts of a piece of music, and the limitations of

650
00:37:58,840 --> 00:38:01,719
Speaker 1: human hearing also play an important part. So, for example,

651
00:38:01,760 --> 00:38:03,799
Speaker 1: it's very hard for humans to pick up on a

652
00:38:03,920 --> 00:38:08,719
Speaker 1: soft sound that immediately follows a loud sound, much like

653
00:38:08,800 --> 00:38:11,719
Speaker 1: we really only hear the fundamental frequency played on a

654
00:38:11,800 --> 00:38:14,200
Speaker 1: musical instrument. So if you wrote a piece of music

655
00:38:14,239 --> 00:38:17,320
Speaker 1: that has a really loud moment followed immediately by a

656
00:38:17,440 --> 00:38:20,160
Speaker 1: very soft one, chances are no one would ever hear

657
00:38:20,200 --> 00:38:22,600
Speaker 1: the soft part. This also plays a big part in

658
00:38:22,680 --> 00:38:26,440
Speaker 1: strategies that revolve around audio compression. If you've listened to

659
00:38:26,480 --> 00:38:29,360
Speaker 1: my episodes about the MP three format, you know that

660
00:38:29,480 --> 00:38:33,640
Speaker 1: some forms of compression rely on what's called a lossy formula.

661
00:38:34,000 --> 00:38:37,320
Speaker 1: As the name implies, lossy compression is able to reduce

662
00:38:37,360 --> 00:38:41,400
Speaker 1: file size by ditching some of that data, you lose

663
00:38:41,719 --> 00:38:45,400
Speaker 1: some of the information. The goal of lossy compression is

664
00:38:45,520 --> 00:38:48,640
Speaker 1: to get rid of data without perceivably changing the quality

665
00:38:48,800 --> 00:38:53,000
Speaker 1: of the sound file or reducing any perceivable quality as

666
00:38:53,040 --> 00:38:55,600
Speaker 1: much as possible. The first way to do that is

667
00:38:55,600 --> 00:39:00,200
Speaker 1: to identify any sounds that theoretically should be imperceptible to

668
00:39:00,239 --> 00:39:02,319
Speaker 1: the average person and then just getting rid of them,

669
00:39:02,320 --> 00:39:04,680
Speaker 1: because if you can't hear it, why would you keep it.

670
00:39:05,200 --> 00:39:09,160
Speaker 1: But as we've learned, stuff like overtones are also important.

671
00:39:09,360 --> 00:39:13,360
Speaker 1: They are what characterized the quality of a particular musical instrument,

672
00:39:13,760 --> 00:39:17,520
Speaker 1: even though we don't directly perceive the pitches underneath those

673
00:39:17,560 --> 00:39:21,120
Speaker 1: overtones as distinct notes. So lossy formats have to take

674
00:39:21,160 --> 00:39:24,280
Speaker 1: that into account, or the compressed file is just gonna

675
00:39:24,280 --> 00:39:29,200
Speaker 1: sound weird. Guitars won't sound like guitars, for example. So interestingly,

676
00:39:29,560 --> 00:39:32,680
Speaker 1: there's a lot of psychology that goes into audio compression

677
00:39:33,200 --> 00:39:36,360
Speaker 1: by combining our understanding of physics, even if it was

678
00:39:36,400 --> 00:39:40,320
Speaker 1: a limited understanding or perhaps more of an observation without

679
00:39:40,360 --> 00:39:45,000
Speaker 1: full understanding, with our appreciation for which frequencies are pleasing

680
00:39:45,040 --> 00:39:47,800
Speaker 1: to us, and the limitations that we have as human beings.

681
00:39:48,320 --> 00:39:51,480
Speaker 1: We can construct various instruments to play into all of this,

682
00:39:52,000 --> 00:39:54,400
Speaker 1: but it all comes down to how can I construct

683
00:39:54,440 --> 00:39:57,720
Speaker 1: something that will vibrate and make those vibrations sound good.

684
00:39:58,800 --> 00:40:02,120
Speaker 1: I'd love to give you history of musical instruments, but

685
00:40:02,239 --> 00:40:06,080
Speaker 1: humanities relationship with music dates back before our relationship with

686
00:40:06,200 --> 00:40:10,840
Speaker 1: written language. Among the oldest instruments ever discovered where flutes

687
00:40:10,920 --> 00:40:14,400
Speaker 1: from European caves. These flutes were made out of bird

688
00:40:14,480 --> 00:40:17,560
Speaker 1: bone and mammoth ivory and they were built more than

689
00:40:17,640 --> 00:40:21,680
Speaker 1: forty thousand years ago. And keep in mind I said

690
00:40:21,680 --> 00:40:24,640
Speaker 1: these were the earliest ones that we've discovered. Who knows

691
00:40:24,760 --> 00:40:28,560
Speaker 1: when humans first made musical instruments. If I had to guess,

692
00:40:28,719 --> 00:40:32,680
Speaker 1: I would wager that percussion instruments like drums were among

693
00:40:32,719 --> 00:40:36,640
Speaker 1: the earliest. But there are a lot of other ancient examples,

694
00:40:37,360 --> 00:40:40,360
Speaker 1: and one I want to talk about is particularly interesting.

695
00:40:40,360 --> 00:40:43,200
Speaker 1: I want to close out with this ancient musical instrument

696
00:40:43,239 --> 00:40:45,799
Speaker 1: because there are people who still use it today and

697
00:40:45,880 --> 00:40:50,399
Speaker 1: it's super cool. It's called the bull roarer. It's hard

698
00:40:50,400 --> 00:40:53,440
Speaker 1: for me to say that word, being Southern bull roarer.

699
00:40:53,880 --> 00:40:55,959
Speaker 1: I just want to make it a two syllable word.

700
00:40:56,360 --> 00:40:59,680
Speaker 1: But these were used as far back as the Stone Age.

701
00:41:00,040 --> 00:41:03,560
Speaker 1: Typically these consist of a slat of wood, and it's

702
00:41:03,600 --> 00:41:06,319
Speaker 1: usually shaped so that there's an edge on either side

703
00:41:06,360 --> 00:41:09,040
Speaker 1: of the slat of wood. So think of like a ruler,

704
00:41:09,160 --> 00:41:12,040
Speaker 1: but you've you've shaved the edges of the ruler down

705
00:41:12,080 --> 00:41:14,560
Speaker 1: so that it's kind of like the propeller on an

706
00:41:14,560 --> 00:41:18,120
Speaker 1: old prop plane. And you wrap a chord around one end,

707
00:41:18,280 --> 00:41:20,959
Speaker 1: or you may drill a hole, loop the cord through

708
00:41:21,000 --> 00:41:23,680
Speaker 1: the hole and tie it off, and then you give

709
00:41:24,200 --> 00:41:26,680
Speaker 1: the cord a little bit of a twist, and then

710
00:41:26,719 --> 00:41:28,880
Speaker 1: you hold the other end of the cord and you

711
00:41:28,920 --> 00:41:34,000
Speaker 1: start swinging the bull roarer in a circle. As it swings,

712
00:41:34,280 --> 00:41:37,720
Speaker 1: the cord begins to untwist, and then it continues twist

713
00:41:37,800 --> 00:41:41,640
Speaker 1: in the opposite direction before reversing the process. So the

714
00:41:41,680 --> 00:41:44,960
Speaker 1: bull roarer moves along the path of the circle, and

715
00:41:45,000 --> 00:41:47,320
Speaker 1: as it's doing so, it's turning because of the cord

716
00:41:47,360 --> 00:41:51,480
Speaker 1: twisting and untwisting, And this movement through the air creates

717
00:41:51,480 --> 00:41:56,000
Speaker 1: the vibrations that travel as sound. Several factors can influence

718
00:41:56,080 --> 00:41:59,360
Speaker 1: the pitch of that sound. That includes the length of

719
00:41:59,400 --> 00:42:03,920
Speaker 1: cord ear using, which obviously determines the diameter of the

720
00:42:03,960 --> 00:42:07,520
Speaker 1: circular path that the bull roarer is taking. Also the

721
00:42:07,600 --> 00:42:10,560
Speaker 1: frequency with which you are swinging this in a circle,

722
00:42:10,800 --> 00:42:13,440
Speaker 1: the amount of twists that was in the cord, and

723
00:42:13,480 --> 00:42:16,920
Speaker 1: even the plane of rotation, whether it's vertical versus horizontal.

724
00:42:16,960 --> 00:42:21,560
Speaker 1: For example, bull roarers were used by many ancient peoples

725
00:42:21,600 --> 00:42:25,439
Speaker 1: as a means of communication by varying the pitch, which

726
00:42:25,480 --> 00:42:27,880
Speaker 1: again you could do in all those different ways I

727
00:42:27,960 --> 00:42:32,480
Speaker 1: just mentioned. You could send simple messages several miles away

728
00:42:32,520 --> 00:42:35,640
Speaker 1: because the sound would just travel so far. Those low

729
00:42:35,719 --> 00:42:40,120
Speaker 1: frequencies travel pretty well. The fact that you're talking about

730
00:42:40,840 --> 00:42:45,880
Speaker 1: longer wavelengths um and and lower frequencies, the energy is

731
00:42:45,960 --> 00:42:50,080
Speaker 1: much more efficient at far distance travel, and so these

732
00:42:50,120 --> 00:42:54,279
Speaker 1: were used by early civilizations for thousands of years as

733
00:42:54,320 --> 00:42:57,320
Speaker 1: a way for people to send distant messages back and forth.

734
00:42:57,440 --> 00:43:01,239
Speaker 1: Pretty simple messages, but distant ones that could be very

735
00:43:01,239 --> 00:43:05,440
Speaker 1: helpful for early civilizations. In the next episode, I'm going

736
00:43:05,480 --> 00:43:08,279
Speaker 1: to go into more detail about how specific types of

737
00:43:08,360 --> 00:43:12,279
Speaker 1: musical instruments actually work, how they create the sounds they make.

738
00:43:12,920 --> 00:43:15,440
Speaker 1: I'm going to focus on the musical instruments found in

739
00:43:15,520 --> 00:43:19,920
Speaker 1: Western orchestras, because to cover all musical instruments would require

740
00:43:19,960 --> 00:43:22,680
Speaker 1: its own podcast series, and if I were to cover

741
00:43:22,719 --> 00:43:25,560
Speaker 1: how bagpipes works, I would probably need a therapist. But

742
00:43:25,880 --> 00:43:28,640
Speaker 1: I hope you guys enjoyed this overview of the science

743
00:43:29,000 --> 00:43:31,960
Speaker 1: of producing sounds. If any of you out there have

744
00:43:32,000 --> 00:43:35,120
Speaker 1: any suggestions for future topics I should cover, whether it's

745
00:43:35,120 --> 00:43:38,399
Speaker 1: a specific technology, a type of tech like I'm doing now,

746
00:43:38,880 --> 00:43:42,080
Speaker 1: a company in technology, or a very important person in tech,

747
00:43:42,520 --> 00:43:45,359
Speaker 1: or anything along those lines. Let me know. You can

748
00:43:45,360 --> 00:43:48,480
Speaker 1: reach out on Facebook or Twitter. The handover both is

749
00:43:48,560 --> 00:43:53,320
Speaker 1: Tech Stuff HSW and I'll talk to you again really soon.

750
00:43:54,040 --> 00:44:00,760
Speaker 1: Y tex Stuff is an I heart Rate deo production.

751
00:44:01,000 --> 00:44:03,799
Speaker 1: For more podcasts from I heart Radio, visit the I

752
00:44:03,920 --> 00:44:07,160
Speaker 1: heart Radio app, Apple Podcasts, or wherever you listen to

753
00:44:07,200 --> 00:44:12,680
Speaker 1: your favorite shows. H