Speaker 1: Welcome to tech Stuff, a production from I Heart Radio.
Speaker 1: Hey there, and welcome to tech Stuff. I'm your host,
Speaker 1: Jonathan Strickland. I'm an executive producer with I Heart Radio
Speaker 1: and I love all things tech and recently I received
Speaker 1: a tweet from Twitter user Salvatore del Knock, a k
Speaker 1: A non juror, asking if I would do a breakdown
Speaker 1: on how analog to digital and digital to analog audio
Speaker 1: converters work. And that's a great request. Um, it is
Speaker 1: incredibly technical when you really get down to it. So
Speaker 1: I'm going to do a very high level view of
Speaker 1: the concept because otherwise we're gonna have to get into
Speaker 1: the various methodologies that DAC and a d c's work,
Speaker 1: and uh, it would quickly become like a technical manual.
Speaker 1: But if people want that, then I can do a
Speaker 1: subsequent episode and go into more detail. But one of
Speaker 1: the things about this is that lets us talk about
Speaker 1: the differences between analog and digital audio and why converters
Speaker 1: are necessary in the first place, and to open up
Speaker 1: the eternal argument about whether one is inherently better than
Speaker 1: the other. This one goes out to all you audio
Speaker 1: files out there, so get ready to send me angry messages,
Speaker 1: because no matter what I say, some of y'all are
Speaker 1: going to get upset. Anyway, let's start with what it
Speaker 1: means to be analog versus digital. Now, when I was
Speaker 1: a young boy, nobody loved me. I was a poor
Speaker 1: boy from a poor family. No, hang on, that's now,
Speaker 1: that's Queen's bohemian rhapsty Now, when I was a young boy,
Speaker 1: analog was the standard. Digital did not even enter into
Speaker 1: my awareness until I was a teenager, when compact discs
Speaker 1: were starting to become popular. They had been around for
Speaker 1: a while before I was a teenager, but I was
Speaker 1: not really aware of them, because I mean, I grew
Speaker 1: up in rural Georgia. We would get technology a few
Speaker 1: years behind everybody else. Anyway, I grew up thinking analog
Speaker 1: essentially meant old and digital meant new, Like that was
Speaker 1: the sort of the abstract distinction between the two in
Speaker 1: my head. But the differences are obviously more complicated than that,
Speaker 1: and we need to understand how sound works, which I
Speaker 1: know I've covered many many times, but it's important so
Speaker 1: that we know how the analog and digital methods of
Speaker 1: recording and thus reproducing and eventually playing back sound. You
Speaker 1: know how they work with relation to the original sound
Speaker 1: that existed. So sound is, when you really get down
Speaker 1: to it, vibration or pressure waves. Now, we mostly experienced
Speaker 1: sound by hearing these vibrations travel through the air, but
Speaker 1: you can also experience this underwater. Sound can move through
Speaker 1: different media, including solid material. Like if you put your
Speaker 1: ear against a table, a really long table, and some
Speaker 1: one on the other end is tapping very lightly on
Speaker 1: that table, you'll hear it. And it's not because the
Speaker 1: sound is traveling effectively through the air, though it is
Speaker 1: doing a little bit of that too, but that it
Speaker 1: travels through the table to you. Sound also travels at
Speaker 1: different speeds through different media, and in fact, stuff like
Speaker 1: air temperature can affect how quickly sound travels, which is
Speaker 1: why when we talk about the speed of sound, we
Speaker 1: technically actually need to be a little more specific than that.
Speaker 1: So the standard way of describing the speed of sound
Speaker 1: is to say that it moves at three per second
Speaker 1: in dry air at twenty celsius, that's about sixty eight fahrenheit.
Speaker 1: And if you start changing those parameters, you know, if
Speaker 1: you introduce, say a lot of humidity into the air,
Speaker 1: or you change the air temperature like it goes up
Speaker 1: or it goes down. Well, sound will travel at a
Speaker 1: slightly different speed than at that standard I was talking about.
Speaker 1: Now I could get into how the vibrations cause air
Speaker 1: molecules to move back and forth, creating little changes in
Speaker 1: air pressure. And it's these pressure waves, these air fluctuation changes,
Speaker 1: that our ear drums pick up and transfer to our
Speaker 1: inner ears. That's where special nerves pick up these fluctuations
Speaker 1: in our inner ears, and then our brains process those
Speaker 1: those nerve signals as sound. But most of this isn't
Speaker 1: important for the rest of this episode, so instead, let's
Speaker 1: talk about sound waves, all right. So we can think
Speaker 1: of a vibration as something in which a particle is
Speaker 1: moved out of its usual place and then it snaps
Speaker 1: back to its usual place, and it might do this
Speaker 1: several times. Think of a guitar string. If you pluck
Speaker 1: a guitar string, you're pulling the string out of where
Speaker 1: it usually sits, and then it snaps back and forth
Speaker 1: and oscillates around its normal position until it settles down again.
Speaker 1: So we can describe the number of times that a
Speaker 1: particle does as a frequency, you know, or the number
Speaker 1: of times a string goes from one point all the
Speaker 1: way across and back to that starting point over the
Speaker 1: course of a second. So with sound, we usually use
Speaker 1: the unit hurts to measure frequency. If a particle only
Speaker 1: did one cycle of vibration per second, if it took
Speaker 1: a full second for it to go from the you know,
Speaker 1: the one crest to the next crest, uh, then it
Speaker 1: would be one hurts. That would also, by the way,
Speaker 1: be a frequency that was way too low for us
Speaker 1: to hear. Typical human hearing has a range of around
Speaker 1: twenty hurts at the low end, to twenty thousand hurts
Speaker 1: or twenty killer hurts, in other words, on the high end.
Speaker 1: So for stuff vibrating in a cycle that's twenty times
Speaker 1: a second all the way up to twenty thousand times
Speaker 1: a second, that's something we could potentially hear. Now. I
Speaker 1: say potentially because that is typical human hearing. There are
Speaker 1: people who can hear outside of that range a little bit,
Speaker 1: and then there are some of us, especially as we
Speaker 1: get older, who can hear a more narrow range of frequencies.
Speaker 1: But frequency is just one part of how we describe sound.
Speaker 1: We can also describe sound by how loud it is.
Speaker 1: The volume of sound. So from a physics perspective, we
Speaker 1: can think of this is how much pressure the sound
Speaker 1: places upon our ear drums. You know how dramatic those
Speaker 1: fluctuations and air pressure are. In other words, But loudness
Speaker 1: isn't just down to physics. The way we experience loudness
Speaker 1: depends not just on that sound pressure itself, but stuff
Speaker 1: like psychoacoustics. That's how our brains perceive sound in the
Speaker 1: first place. But now we've got two criteria we can
Speaker 1: use to assign to any sound correct Like, we can
Speaker 1: talk about the frequency of that sound, you know, how
Speaker 1: frequently that those particles are vibrating, And then we can
Speaker 1: also talk about the displacement of those particles vibrating, or
Speaker 1: what we might think of as the loudness or volume
Speaker 1: of that sound. We could then plot a sound wave
Speaker 1: as a transverse wave on a graph, and we could
Speaker 1: have the X axis, you know, the horizontal axis of
Speaker 1: this graph representing the passage of time. So on the
Speaker 1: left side we might say zero, and we say time
Speaker 1: increases as you go to the right. The y axis
Speaker 1: we could have being displacement, which kind of you know,
Speaker 1: amplitude or volume in other words, and we could then
Speaker 1: plot all the points where a particular vibrating particle would
Speaker 1: occupy over a given span of time. If we had
Speaker 1: a sound of a steady frequency, then we would end
Speaker 1: up with a wave that would look a lot like
Speaker 1: a sign or cosign wave. The distance between two consecutive
Speaker 1: crests of this wave would be the wavelength for that sound,
Speaker 1: and the sounds wavelength has an inversely proportional relationship with
Speaker 1: the sounds frequency, So the higher the frequency of sound,
Speaker 1: the shorter the wavelength will be. So deep bay Ace
Speaker 1: notes would have sound waves that have much longer wavelengths
Speaker 1: than very high pitched high frequency notes. Uh frequency relates
Speaker 1: to pitch. There isn't like an easy mathematical way we
Speaker 1: can kind of relate pitch, by the way, There are
Speaker 1: easy ways we can relate frequencies, but it gets a
Speaker 1: little tricky anyway. The reason I even talk about plotting
Speaker 1: sound waves at all is that it makes us easier
Speaker 1: for us to consider the differences between analog and digital
Speaker 1: audio recording. Keep in mind, if we plotted that sound wave,
Speaker 1: that's not that's not the physical sound wave that we've
Speaker 1: just plotted. That's our description of that sound wave, its frequency,
Speaker 1: and its loudness. Um The classic sign wave like depiction
Speaker 1: of the sound wave shows us that there's a continuous
Speaker 1: representation of sound across time. It is unbroken. We can
Speaker 1: put plot, you know, even complicated sounds with changes in
Speaker 1: amplitude and frequency, and the shape of the waves tells
Speaker 1: us a little bit about the tambre or quality of sound. Now,
Speaker 1: by quality, I don't mean, oh, this sound is very
Speaker 1: good quality or this sound is really bad quality. Instead,
Speaker 1: I'm talking about the elements that differentiate say piano playing
Speaker 1: middle C from a guitar playing that same note middle C.
Speaker 1: Both instruments are producing the same note at the same frequency,
Speaker 1: assuming both instruments are you know, properly tuned, and both
Speaker 1: of them are using the same pitch tuning, but you
Speaker 1: would hear a difference in the type of sound between them, right,
Speaker 1: A piano and a guitar sound different. Otherwise all instruments
Speaker 1: would produce exactly the same kind of sound as each other.
Speaker 1: But you know, you can tell the difference between a
Speaker 1: piano and a guitar, or a clarinet or a flute
Speaker 1: or whatever. The tambre is different, even if the instruments
Speaker 1: are all producing you know, technically the same frequency, even
Speaker 1: at the same volume. This leads us to the fact
Speaker 1: that sound is this continuous thing for us. It isn't
Speaker 1: happening in discrete units. It's kind of like the difference
Speaker 1: between jumping into a pool filled filled with water, which
Speaker 1: is you know, continuous to us because we can't you know,
Speaker 1: experience it down on the molecular level, or jumping into
Speaker 1: a pool that's filled with plastic balls. So to us,
Speaker 1: sound is kind of like a fluid, and analog recording
Speaker 1: captures that. The analog approach to recording is older than digital.
Speaker 1: So way way back in the nineteenth century, folks like
Speaker 1: Alexander Graham Bell, we're trying to figure out how to
Speaker 1: transmit the human voice across great distances using electricity, and
Speaker 1: the microphone was one half of what was needed to
Speaker 1: do this, the loud speaker being the other half. And
Speaker 1: the basic way a standard microphone works is to convert
Speaker 1: sound that continuous you know phenomena of pressure wave changes
Speaker 1: to a varying electric signal, an electric signal that has
Speaker 1: varying voltage. This is another continuous phenomena, right, it's unbroken,
Speaker 1: it's it's like another wave. Here's how it works. So
Speaker 1: inside an analog microphone is a tiny little diaphragm, typically
Speaker 1: made of very thin plastic, and it behaves in a
Speaker 1: way similar to how our ear drums work in our ears.
Speaker 1: So when sound, you know, these pressure waves hit that microphone,
Speaker 1: it moves the diaphragm back and forth, and the diaphragm
Speaker 1: is actually attached to an electro magnet. A simple microphone
Speaker 1: could have a permanent magnet inside it, and wrapped around
Speaker 1: this permanent magnet is a little coil of metal wire
Speaker 1: that connects to the diaphragm. So the diaphragm moves the coil,
Speaker 1: which then moves along the length of this permanent magnet.
Speaker 1: That introduces a fluctuating magnetic field, or rather, you know
Speaker 1: the effect of a fluctuating magnetic field. The permanent magnets
Speaker 1: magnetic field is stable, but moving a coil through a
Speaker 1: magnetic field, it's the same thing as if you were
Speaker 1: to fluctuate a magnetic field around a you know, non
Speaker 1: moving coil, you get the same effect. Now, the laws
Speaker 1: of electromagnetism tell us that if you have a conductive
Speaker 1: material and it encounters a fluctuating magnetic field, that field
Speaker 1: will then induce an electric current in the conductive material.
Speaker 1: So now you've got the microphone producing an electric current,
Speaker 1: and again the voltage of this current varies depending upon
Speaker 1: the sound hitting the microphone. That means the microphone is
Speaker 1: a type of transducer. That's a device that converts one
Speaker 1: form of energy, in this case acoustic pressure, into another
Speaker 1: form electric signals. Now, you could send this electric current
Speaker 1: with varying voltage somewhere to do something else interesting, like
Speaker 1: you could have it go directly to allowed speaker for playback. Now,
Speaker 1: of course, this electric current is really uh there are
Speaker 1: you know, very small elements in your microphone, right, so
Speaker 1: it cannot produce an incredibly strong electric current. So typically
Speaker 1: you would first pass this electric current through an amplifier,
Speaker 1: which increases the strength of the signal. I'm not going
Speaker 1: to go into how amplifiers work. I've talked about in
Speaker 1: other episodes, and it would mean that this this episode
Speaker 1: would go like an hour and a half long if
Speaker 1: I were to to dive into that. The important thing
Speaker 1: to think of is that amplifiers take incoming week signals
Speaker 1: and then push out a stronger version of that same signal.
Speaker 1: Assuming the amplifiers working properly, then that signal could go
Speaker 1: to a speaker and you would have the same process
Speaker 1: that you had with the microphone, only in reverse. The
Speaker 1: speaker also has a voice coil inside it, a coil
Speaker 1: of you know, conductive of metal wire, and also a
Speaker 1: magnet inside the loudspeaker. So the incoming current goes to
Speaker 1: the wire, and we know by the laws of electro
Speaker 1: magnetism that this means the flowing current through the wire
Speaker 1: will also produce a magnetic field. I mean, this is
Speaker 1: how electro magnetism works, and that this magnetic field will
Speaker 1: then pull and push against the magnetic field generated by
Speaker 1: the permanent magnet that's already inside the speaker, and this
Speaker 1: in turn creates the force that pushes and pulls the
Speaker 1: cone inside the speaker that connects to another diaphragm. This
Speaker 1: is a much larger diaphragm than the one that's on
Speaker 1: the microphone on the other side. Right, Because you've boosted
Speaker 1: the electric signal, it can then have enough power to
Speaker 1: move this larger diaphragm. So this larger diaphragm begins to
Speaker 1: move in and out, and it's pushing and pulling air
Speaker 1: and it's just recreating the acoustic pressure waves that we're
Speaker 1: used to go into the microphone and generate the electric
Speaker 1: signal in the first place, so you're kind of preserved
Speaker 1: this experience from sound going into a microphone. The microphone
Speaker 1: as a transducer, transforming that acoustic pressure into an electric
Speaker 1: current with varying voltage, sending that to an amplifier, and
Speaker 1: then a speaker, which then does the opposite. It's also
Speaker 1: a transducer. It takes this electric current with varying voltage
Speaker 1: and converts it back into acoustic pressure and we get
Speaker 1: the playback. That's an analog chain from start to finish. Now,
Speaker 1: if you've got a good quality microphone and a good
Speaker 1: amplifier and a good speaker, you can transmit sound pretty effectively.
Speaker 1: And because the whole process is using that continuous and
Speaker 1: varying signal, it is analogous to the experience of hearing
Speaker 1: the sound itself. We've transformed the energy from one kind
Speaker 1: to another, but apart from that, it is an unbroken chain. Now,
Speaker 1: analog media includes stuff like magnetic tape and vinyl records,
Speaker 1: which are produced in a way where you are transmitting
Speaker 1: analog signals and they are effectively carved into a surface
Speaker 1: that then can be picked up with a stylus on
Speaker 1: a turntable and then converted back into an electric signal
Speaker 1: that then can be sent to speakers. So either way
Speaker 1: you are preserving that analog signal with magnetic tape. You've
Speaker 1: got a recording device set up that takes that varying
Speaker 1: electric signal from the recording and then creates a magnetic
Speaker 1: field with the the writer the right head. Uh, And
Speaker 1: you've got a little electro magnet in this thing, and
Speaker 1: that magnetic field rearranges particles that aren't a strip of
Speaker 1: plastic tape. That's how cassette tapes work. That's all VHS
Speaker 1: tapes work. So attached to this strip of plastic that
Speaker 1: is the actual tape in a tape, are these tiny
Speaker 1: magnetic particles that are bound to that plastic. And by
Speaker 1: applying the magnetic field to the tape, using in a
Speaker 1: tiny electro magnet, you can change the direction that these
Speaker 1: particles are facing on the tape itself. So this process
Speaker 1: arranges particles on magnetic tape in a specific way to
Speaker 1: record that original electric signal you were using. The magnetic
Speaker 1: particles represent the original signal and then in turn represents
Speaker 1: the sound that was used to generate the electric signal
Speaker 1: during the recording process. So when you play a tape back,
Speaker 1: the tape passes underneath an electro magnet at a distance
Speaker 1: that's close enough that the electro magnet is picking up
Speaker 1: the magnetic fields of all those tiny particles, and the
Speaker 1: particles have been arranged in patterns because of that, you know,
Speaker 1: recording process, right. So the fluctuating magnetic field that is
Speaker 1: created because these particles are now passing by an electro
Speaker 1: magnet are again reversing that process. The electro magnet starts
Speaker 1: to generate an electric signal because of that magnetic field,
Speaker 1: and then can go to an amplifier and then go
Speaker 1: out to speakers. So again we use a lot of
Speaker 1: transformational processes to record this sound, right, because you're in
Speaker 1: this case, we took pressure waves, vibrations, The sound went
Speaker 1: into a microphone, creates an electric current with varying voltage.
Speaker 1: That electric current then goes to a tape recorder essentially
Speaker 1: that uses magnetic fields to record onto tape. We take
Speaker 1: that tape, we put that tape into a tape player,
Speaker 1: and that magnetic record then produces an electric current in
Speaker 1: our tape player, which goes to an amplifier and then
Speaker 1: goes to drive speakers and replicate the sound that we
Speaker 1: record in the first place. So again we transformed things
Speaker 1: multiple times, but the analogous sound process has remained stable. Now,
Speaker 1: there's a lot in this process that I have not covered.
Speaker 1: The equipment and methods you use in recording and playback
Speaker 1: determine whether or not the copy you have is a
Speaker 1: really like accurate representation of the original sound like does
Speaker 1: it sound like you were actually there? Or is the
Speaker 1: nuance lost? And the same is true for a back.
Speaker 1: Playback on a really sophisticated system will likely sound better
Speaker 1: than one that's played on some super cheap stereo. Though
Speaker 1: pretty quickly you do reach a point where the returns
Speaker 1: are harder to detect, right like where you might listen
Speaker 1: to something on a good system, and then you might
Speaker 1: listen to that same thing on what's considered like the
Speaker 1: highest of high end systems, and you might not be
Speaker 1: able to tell a whole lot of difference. But the
Speaker 1: basics for analog recording and playback are all there. Now.
Speaker 1: When we come back, we'll talk about the digital approach,
Speaker 1: but first let's take a quick break. Okay, So now,
Speaker 1: we've got an idea of how the analog process of
Speaker 1: recording and playback works. We transform stuff, but we still
Speaker 1: have a continuous signal that represents sound, which is, you know,
Speaker 1: a continuous phenomena as sound changes, as the pitch and
Speaker 1: the frequency shifts, or as the volume changes, or as
Speaker 1: different instruments or voices produced sounds. All those subtle and
Speaker 1: maybe not so subtle shifts are part of that recording method.
Speaker 1: It's an unbroken wave. Digital recording uses a different approach
Speaker 1: in a way. Digital recording is like taking snapshots of
Speaker 1: what is going on during a recording session. And I
Speaker 1: thought of a kind of goofy analogy to sort of
Speaker 1: explain what I mean. So imagine for a moment that
Speaker 1: you are in a soundproofed room and you cannot hear
Speaker 1: anything that's going on outside of this room. However, you
Speaker 1: do have a little panel like almost like a hatch
Speaker 1: in this room, and it happens to be facing a
Speaker 1: really big orchestra pit, and the orchestra is playing. And
Speaker 1: you know this because there's a light in the room
Speaker 1: that lights up when the orchestra is playing. But you
Speaker 1: can't hear anything because the rooms sound proved However, next
Speaker 1: to the panel is a button, and if you press
Speaker 1: the button, the panel opens up, but only for a
Speaker 1: split second. Next to the panel, you have a table,
Speaker 1: you get some paper, you got a pen, and your
Speaker 1: job is to press the button, listen for that split second,
Speaker 1: and then write down what you think is going on
Speaker 1: in the orchestra. You know, like you could write down
Speaker 1: everything from the specific instruments that you're hearing, the relative
Speaker 1: volume of those instruments, any sort of harmonies you're hearing.
Speaker 1: Maybe you're even just trying to play name that tune. Now,
Speaker 1: let's say there's some other rules in place too. If
Speaker 1: you push the button, you are not allowed to push
Speaker 1: it again until five seconds have passed. So every five
Speaker 1: seconds you get another instant of sound as the panel
Speaker 1: opens and closes. This is that little snapshot of what's happening.
Speaker 1: It would be really hard to accurately describe the music
Speaker 1: because you wouldn't have a lot of information to go by, right,
Speaker 1: you would just have this instant of sound every five seconds.
Speaker 1: It might as well be noise at that point. But
Speaker 1: then let's say we start to decrease the delay, where
Speaker 1: you get to have the panel open so that you're
Speaker 1: getting these instants is of sound more close together. As
Speaker 1: that gets closer and closer, it will start to sound
Speaker 1: more like uninterrupted music. Maybe we even rig up the button.
Speaker 1: We tape down the button so it's always pressed down,
Speaker 1: and the panel still has to open and close, but
Speaker 1: it can open immediately after it shuts, so it's effectively
Speaker 1: a shutter. At a fast enough rate, you wouldn't necessarily
Speaker 1: even notice the shutters effect on the music. To you.
Speaker 1: It would sound unbroken if it were fast enough, And
Speaker 1: then you could accurately describe the music you could write down,
Speaker 1: you know, depending on how quickly you can write, you
Speaker 1: can write down a really accurate explanation of what is
Speaker 1: going on with the music, or maybe you're just identifying
Speaker 1: what pieces playing. But uh, you know, in this case,
Speaker 1: if you've got that shutter going at a high enough rate,
Speaker 1: it's almost like you're not in a soundproof room at all. Well,
Speaker 1: this kind of is how digital recording works. So rather
Speaker 1: than preserving an unbroken sign Knoll, the digital process breaks
Speaker 1: up a signal into discrete units. It has to because digital,
Speaker 1: when we get down to it, we're talking about binary
Speaker 1: data zeros and ones. You cannot use zeros and ones
Speaker 1: to uh to to do anything other than talk about
Speaker 1: discrete units. It can't be a continuous thing. Now. As
Speaker 1: I mentioned earlier in this episode, there are a lot
Speaker 1: of quantifiable elements we can look at when it comes
Speaker 1: to sound. We can describe how loud it is, or
Speaker 1: what frequency or pitch it is. We can describe the
Speaker 1: timbre or quality of the sound. That that kind of
Speaker 1: gets us into areas that are a little less concrete
Speaker 1: at least in human language and digital equipment like computers
Speaker 1: are pretty good at handling things that are discrete and quantifiable.
Speaker 1: This is the realm of computers. And remember, ultimately computers
Speaker 1: are relying on those zeros and ones to describe everything.
Speaker 1: Just to be clear, to get to this point, we
Speaker 1: would need to use an analog to digital converter, but
Speaker 1: I'm actually gonna circle round back to that later on.
Speaker 1: For now, we're just going to focus on the basics
Speaker 1: of digital recording because understanding that makes the whole you know,
Speaker 1: a D C and d a C stuff way more
Speaker 1: easy to understand. So, the way digital recording systems work
Speaker 1: is that they take snapshots of a continuous wave. They're
Speaker 1: measuring precisely all the elements at that moment in time
Speaker 1: of the wave and it's or signal signal is probably
Speaker 1: a better word than wave. Really, we're talking about the
Speaker 1: electric signal generated as you're using a transducer to pick
Speaker 1: up sound from you know, wherever. So in this way,
Speaker 1: they're like that panel in that soundproof room. If the
Speaker 1: sample rate is too low, if you are not sampling
Speaker 1: the signal frequently enough, then you do not get an
Speaker 1: accurate representation of that original signal. You know, You're you're
Speaker 1: having to make a lot of guesses of what's happening
Speaker 1: between each snapshot. Just like if you had a camera
Speaker 1: and you were taking pictures of a fast moving, you know,
Speaker 1: scenario in front of you. If the rate of which
Speaker 1: you're taking pictures is pretty slow, you've got to make
Speaker 1: a lot of interpretation of what happened between picture one
Speaker 1: and picture two, and picture two in picture three. Same
Speaker 1: thing with these digital recording systems. If you were to
Speaker 1: try and play a recording like that back, it would
Speaker 1: not sound very good because it would not be a
Speaker 1: good representation of the original signal. So you need a
Speaker 1: really fast sample rate to get an accurate representation of
Speaker 1: what was really happening. This is the major difference between
Speaker 1: analog and digital. Analog is continuous and unbroken. Digital is discreet.
Speaker 1: But if you are using a very fast sample rate,
Speaker 1: you can create a digital record of a continuous signal
Speaker 1: that to human ears appears to be continuous itself. Again,
Speaker 1: if that shutter is opening and closing fast enough, it's
Speaker 1: almost like it's not even there. Now, let's imagine that
Speaker 1: we've got two graphs that are showing the same signal, right,
Speaker 1: and on the left side we've got the analog signal represented,
Speaker 1: and on the rights that we've got the digital signal. Now,
Speaker 1: let's say at first glance, these two are identical. They
Speaker 1: both look like, you know, a typical sign wave. But
Speaker 1: then you zoom into the analog representation. But no matter
Speaker 1: how how far you zoom in, you see it's just
Speaker 1: a continuous, unbroken line that's representing this this signe wave. Now,
Speaker 1: let's say we take the digital one and we zoom
Speaker 1: way in. Well, as we zoom wag in, we and
Speaker 1: we get closer, we see that rather than being continuous,
Speaker 1: it's actually a series of discrete moments, like almost like
Speaker 1: steps or stairs. That's kind of what we're talking about here.
Speaker 1: The question is how many stairs do we use? Like,
Speaker 1: what's the resolution that we're using here. You can kind
Speaker 1: of think of it like megapixels in a picture. If
Speaker 1: you don't have a lot of megapixels, then you might
Speaker 1: see some blockiness in a photo once you get to
Speaker 1: a certain density, depending on you know, the size of
Speaker 1: the image you're looking at, Like if you're looking at
Speaker 1: on the side of a building, you're gonna need a
Speaker 1: lot of megapixels so it doesn't look blocky. But depending
Speaker 1: on that, uh, it may look really smooth. Same sort
Speaker 1: of thing with sound. Now, if you've ever played with
Speaker 1: digital audio recorders, you've probably seen something labeled sample rate
Speaker 1: or project rate. This refers to the number of samples
Speaker 1: that the recording is taking every second, and to record
Speaker 1: a sound, that sample rate has to be fast enough
Speaker 1: to take two samples within one wavelength of every sound
Speaker 1: that's appearing in that in that recording. And remember I
Speaker 1: said that it sounds wavelength is inversely proportional or has
Speaker 1: an inverse proportional relationship to the sounds frequency, So the
Speaker 1: higher frequency sounds have shorter wavelengths, and you do need
Speaker 1: two samples per wavelength to capture the data necessary. To
Speaker 1: have a recording of that sound. If the wavelength is
Speaker 1: too small, then your sample rate will not be sufficient
Speaker 1: to get all, you know, the full information about that
Speaker 1: sound wave. You won't be able to record it, at
Speaker 1: least not accurately. So remember I said the typical range
Speaker 1: of human hearing is between twenty hurts to twenty killer
Speaker 1: hurts or twenty thousand hurts. That's twenty thousand cycles per second,
Speaker 1: and you have to gather two samples per wavelength or
Speaker 1: or cycle. So that means you need a sampling rate
Speaker 1: of at least forty thousand times per second or forty
Speaker 1: killer hurts to be able to sample everything that's within
Speaker 1: the typical human hearing range. Well, a basic sample rate
Speaker 1: that a lot of people will use for various recording
Speaker 1: projects is forty four point one killer hurts, uh, and
Speaker 1: then they go up from there. In fact, we use
Speaker 1: forty eight killer hurts when we're recording our episodes. I'm
Speaker 1: using forty eight killer hurts right now. I had to
Speaker 1: check because I did accidentally do forty four point one
Speaker 1: for an episode a few weeks back, and Sary needed
Speaker 1: to gently remind me that I need to fix that.
Speaker 1: So it's a forty eight Killer Hurts. So I also
Speaker 1: mentioned that we're quantifying all those elements about the sound.
Speaker 1: We want as accurate a representation of the original sound
Speaker 1: as possible. That means we're not just concerned with the
Speaker 1: number of snapshots that we're taking every second. We're also
Speaker 1: concerned with the quality of each of those snapshots. If
Speaker 1: we were using a literal camera to take pictures, we
Speaker 1: would want stuff like the lighting and the lens to
Speaker 1: be perfect so that every single photo we got was
Speaker 1: an accurate representation of what we were seeing when we
Speaker 1: were there. Well, with digital recording, you know, we're not
Speaker 1: talking about lights and cameras. We're talking about how much
Speaker 1: data we're using to describe the original signal. This is
Speaker 1: called bit depth. Bit depth refers to how many potential
Speaker 1: values we can assign to a signal in an effort
Speaker 1: to describe it. The more potential values we can use,
Speaker 1: the more accurately we can describe the signal. So let's
Speaker 1: do another analogy. All right, Let's say that we're in
Speaker 1: a room. It's you and your best friend. Your best
Speaker 1: friends all the way, I across the other side of
Speaker 1: the room, and I hand you a picture. Your job
Speaker 1: is to subscribe that picture to your best friend who's
Speaker 1: across the room. Your best friend cannot see the picture,
Speaker 1: They can only hear your description. Their job is to
Speaker 1: try and recreate the picture, to draw it as you
Speaker 1: describe it. However, I give you some more restrictions. I say,
Speaker 1: you can only use five adjectives. Uh, you can only
Speaker 1: use five sentences, and they have to be simple sentences.
Speaker 1: They can't be compound or complex or anything. Five simple
Speaker 1: short sentences with a maximum of five adjectives to describe
Speaker 1: that picture. Well, chances are your best friend would draw
Speaker 1: something that's kind of similar to the picture I gave you,
Speaker 1: but it wouldn't be an accurate copy of it. Right.
Speaker 1: You might be like, Okay, I can see where you
Speaker 1: got that based upon the description. But let's say we
Speaker 1: repeat this task, and each time we repeat it, I
Speaker 1: give you a little more freedom and how you can
Speaker 1: describe the picture you're looking at to your friend. So
Speaker 1: you get to use more adjectives, you get to use
Speaker 1: more complex sentences, and each time you're given a larger
Speaker 1: set of potential values that you can express to your
Speaker 1: best friend. Well, that's kind of like bit depths. If
Speaker 1: you're using sixteen bit bit depths. That means you're using
Speaker 1: sixteen bits to determine the range of values that can
Speaker 1: describe the signal. So a bit is either a zero
Speaker 1: or a one. With sixteen bits, you can represent up
Speaker 1: to sixty five thousand, five hundred thirty six values. However,
Speaker 1: let's say you were to go to thirty two bit,
Speaker 1: so sixteen to thirty two, you would think, oh, you
Speaker 1: could do twice as many. That's not that's not the case.
Speaker 1: With thirty two bit depth, you wouldn't be talking about
Speaker 1: twice as many as sixteen bit. With thirty two bits,
Speaker 1: you would be able to describe up to four billion,
Speaker 1: two million, nine d sixty seven thousand, two hundred nineties
Speaker 1: six values. So the greater the bit depth, the more
Speaker 1: accurately you can describe something. Essentially, uh So, it's both
Speaker 1: the sample rate and bit depth together that can allow
Speaker 1: a digital system to create a digital recording that represents
Speaker 1: that continuous signal. It was sampling. Again, the digital recording
Speaker 1: is not continuous. If we zoomed way in, we would
Speaker 1: see it's a bunch of these little steps that are
Speaker 1: all linked together. But if the sample rate is high
Speaker 1: enough and the bit depth is great, enough, we can
Speaker 1: reach a point where the human ear really can't discern
Speaker 1: the difference. Does this mean at lower settings we would
Speaker 1: actually notice a difference if you go low enough. Yeah,
Speaker 1: but really, most of the time even sixteen bit is
Speaker 1: sufficient for just plain old recording and playback. However, if
Speaker 1: you want to work on a project. Let's say you're
Speaker 1: an editor and you're you're trying to edit together music
Speaker 1: files or audio files, larger bit depth gives you much
Speaker 1: more space to work in without introducing stuff like distortion.
Speaker 1: This is called headroom. And if you remember the character
Speaker 1: Max Headroom, that name is a pun on this very
Speaker 1: sort of thing. Technically, at the lower rates you get
Speaker 1: deviations from the true sound. You're essentially inserting errors into
Speaker 1: the digital file. Uh As you increase semple rate and
Speaker 1: bit depth, you can decrease those errors until you reach
Speaker 1: a point where any errors that exist are are impossible
Speaker 1: to detect, at least with our natural equipment. Maybe you
Speaker 1: could detect them if you had supersensitive electronic equipment to
Speaker 1: indicate it, but it wouldn't be something that would be
Speaker 1: necessarily perceptible to human ears. One other interesting thing, or
Speaker 1: a couple of interesting things that I should mention with
Speaker 1: sample rates. So I said, like, your sample rate has
Speaker 1: to be fast enough to capture two points of data
Speaker 1: along the wavelength of every sound, and for most of us,
Speaker 1: that hearing range caps out at twenty killer hurts. That
Speaker 1: might lead you to the question, well, why would you
Speaker 1: bother to go higher than forty killer hurts? Now, if
Speaker 1: twenty killer hurts is the limit of human hearing, typical
Speaker 1: human hearing, why go to forty four point one? Well,
Speaker 1: there are some other things that we need to think
Speaker 1: about that play a factor in this. One of those
Speaker 1: are harmonics. Uh Now, harmonics are way too complicated for
Speaker 1: me to really fully get into in this episode. But
Speaker 1: harmonics can actually exist above the range of human hearing
Speaker 1: and yet still shape how we experience a sound. You
Speaker 1: can almost think of it as the harmonics are sculpting
Speaker 1: the sounds we hear. So even harmonics that are outside
Speaker 1: of our hearing range might be affecting the sounds we
Speaker 1: still can here. So we're not hearing the harmonics directly,
Speaker 1: We're rather experiencing how they are affecting the rest of
Speaker 1: the stuff we can perceive. If that makes sense, Well,
Speaker 1: if you're sampling at a rate that's too low to
Speaker 1: capture those harmonics. Those harmonics are not going to be
Speaker 1: in the digital recording, so they won't be in the playback.
Speaker 1: When you listen to it, you lose that sound. So
Speaker 1: when you do listen back, you're gonna be losing those
Speaker 1: effects and you're not going to experience the sound as
Speaker 1: you would had you been in the place when it
Speaker 1: was being recorded. Also, one thing that we can do
Speaker 1: with recordings is we can change the pitch when we
Speaker 1: record stuff. You know, like if you have a digital recording,
Speaker 1: you can digitally change the pitch. In fact, Tari, if
Speaker 1: you would like to digitally alter the pitch of my voice,
Speaker 1: maybe increase the pitch so that I get that kind
Speaker 1: of chipmunk sound to it. That's you know, boosting the
Speaker 1: frequency up or maybe bringing that frequency way down and
Speaker 1: giving me that deep, bass, booming voice that I know
Speaker 1: I'll never have and I'll never be able to really
Speaker 1: play like a baritone in a musical. Feel free to
Speaker 1: do it. The world is your plaything. So you can
Speaker 1: record audio with a sample rate of forty four point
Speaker 1: one killer hurts. Then on playback, maybe you decide you
Speaker 1: want to pitch everything down well, you'll hit a ceiling
Speaker 1: of the sounds that you'll have in that recording once
Speaker 1: you get to killer hurts or so. So, if there
Speaker 1: were sounds that were above killer hurts, you're not really
Speaker 1: going to be able to hear them with the pitched
Speaker 1: down recording. Remember that pitch down recording will bring stuff
Speaker 1: that is outside human hearing into the range of human
Speaker 1: hearing because you've pitched it down. But if your sample
Speaker 1: rate is too slow, too low, in other words, you
Speaker 1: won't have captured those higher pitches. So let's say that
Speaker 1: you're recording something that's in a very very high frequency,
Speaker 1: like beyond the range of human hearing. But then you
Speaker 1: want to do a pitch adjustment so that people can
Speaker 1: actually hear a sound, even though you know normally they
Speaker 1: wouldn't be able to hear it at all because it
Speaker 1: would be outside their range. Maybe you're doing like a
Speaker 1: nature documentary and there's a critter that makes sounds that
Speaker 1: typically we cannot hear, but by pitching it down, you
Speaker 1: can say this is what it sounds like once we
Speaker 1: reduce the pitch. Well, you have to have a sample
Speaker 1: rate that's high enough so that you capture that range
Speaker 1: of sound in the first place. Right, So that's one
Speaker 1: reason why you might want a very high sample rate.
Speaker 1: I just thought that was neat all. Right, we need
Speaker 1: to take another break. When we come back, we'll talk
Speaker 1: about the process we need to follow in order to
Speaker 1: go from analog to digital and back again. It's gonna
Speaker 1: be a lot of us talking about some of the
Speaker 1: stuff we just chatted about, and we'll also talk about
Speaker 1: audio files a little bit. But first let's take another
Speaker 1: quick break. Now, before I dive into the converter's part,
Speaker 1: I should add there are some outliers, right There are
Speaker 1: digital microphones. For example. Now there's some digital microphones that
Speaker 1: are analog at the front end, so in other words,
Speaker 1: they still have the diaphragm, they still have the electromagnet,
Speaker 1: they're still generating an electric current with varying voltage. But
Speaker 1: then they'll have an analog to digital converter built into
Speaker 1: the microphone itself. So you have an A D C
Speaker 1: and it's right there in the device, and then you
Speaker 1: have the signal go to other elements of your recording studio.
Speaker 1: There are other digital microphones that use the pressure waves
Speaker 1: to move elements that immediately convert into digital data, getting
Speaker 1: into that is pretty complicated. They are not super common.
Speaker 1: It's not like that's the type of microphone that everyone
Speaker 1: is using. Um, they're important, but you could argue that
Speaker 1: it's a microphon own and a d C all in
Speaker 1: one because you're taking audio, which is an analog you know, signal,
Speaker 1: and you're converting it immediately into binary or digital information.
Speaker 1: But we're really going to talk about analog to digital
Speaker 1: and digital to analog, which is what most equipment is
Speaker 1: dealing with. When we're speaking about this kind of stuff,
Speaker 1: We're not gonna worry about stuff that's native digital because
Speaker 1: it's just it's not that common. Um like digital speakers
Speaker 1: are a different thing altogether as well, and um yeah,
Speaker 1: we're just gonna wipe those out. We're gonna look at
Speaker 1: what most people use, which is that you know, your
Speaker 1: typical stereo system or your typical audio recording setup. So again,
Speaker 1: typically the end equipment that you use to either record
Speaker 1: or listen to audio, the stuff at the very ends
Speaker 1: of that chain are typically analog in nature. Again, there
Speaker 1: are outliers, but for the vast majority of cases, we're
Speaker 1: talking about an analog device that generates an analog signal
Speaker 1: or plays back an analog signal. So we take an
Speaker 1: analog phenomena, the pressure waves that make up sound. We
Speaker 1: feed that through a transducer to create a different but
Speaker 1: still analog signal, in this case, an electric current with
Speaker 1: variable voltage. But now we get to a point where
Speaker 1: we say, all right, we want to transform that into
Speaker 1: a digital file that quantifies this signal. When we play
Speaker 1: the digital file back, that signal ultimately needs to go
Speaker 1: through some kind of loud speaker for us to hear it.
Speaker 1: Maybe that loud speakers in our headphones, maybe it's a
Speaker 1: stereo system, maybe it's you know, the speaker on your smartphone.
Speaker 1: Maybe it's a sound system in a stadium. But we
Speaker 1: need a way to transform that digital information, all those
Speaker 1: zeros and ones into an electric signal with variable voltage,
Speaker 1: and we probably have to amplify that nal so that
Speaker 1: it's strong enough to drive whatever speakers were using to
Speaker 1: create the sound, which again we experience as an analog phenomena. Now,
Speaker 1: if there was some way that we can interface directly
Speaker 1: with machines and have those digital signals interact with our brains,
Speaker 1: maybe we wouldn't need to do this kind of transformation.
Speaker 1: But as it stands we do have to do this,
Speaker 1: and this is where converters come into play. The converters
Speaker 1: could be standalone devices, or frequently they're worked into the
Speaker 1: design of various pieces of equipment. So for example, a
Speaker 1: USB microphone, if you have one of those that you
Speaker 1: plug into your computer, like I'm using one right now
Speaker 1: to record this, they have that a d C converter
Speaker 1: built into them. And that I'm being repetitive because that's
Speaker 1: analog to digital converter. And then I said a DC converter.
Speaker 1: It's like saying a t M machine. Anyway, the microphone
Speaker 1: still acts just as a traditional analog mic on that end,
Speaker 1: but then the electric signal has to go through a
Speaker 1: converter converts into a digital signal, and that's what transmits
Speaker 1: through the USB cable too, you know, whatever you got
Speaker 1: hooked up to, like in my case, it's my work laptop.
Speaker 1: Now here's the thing. There's more than one way to
Speaker 1: convert an analog signal into a digital one. All of
Speaker 1: these ways get pretty technical talking about the way it's sampled,
Speaker 1: the way it ends up taking these measurements of the signal. So,
Speaker 1: for example, with analog to digital converters or a d
Speaker 1: c s. There are several popular methodologies, but generally speaking,
Speaker 1: they all do the same thing on a big picture scale.
Speaker 1: They all sample a signal. This is the snapshots that
Speaker 1: I was talking about earlier. They look at a signal
Speaker 1: and a specific frequency, like a specific They look at
Speaker 1: the signal a specific number of times every second, and
Speaker 1: they quantified the signal. They measure the signal, which determines
Speaker 1: the resolution that you get of the signal. Obviously, if
Speaker 1: you want high quality sound, you need both a good
Speaker 1: sample rate and a good resolution, which we can think
Speaker 1: of as you know, the accuracy in capturing the nature
Speaker 1: of that signal. You can think of it as an
Speaker 1: A d C is measuring the electric current many many
Speaker 1: times per second and quantifies that measurement as digital data.
Speaker 1: And it's not just like how important is this signal
Speaker 1: at this specific moment in time, but also how important
Speaker 1: are the changes in that signal over greater lengths of time. Now,
Speaker 1: the bit depth we can think of is how detailed
Speaker 1: these measurements can be. So the number of measurements and
Speaker 1: the detail we get together determine the quality of the
Speaker 1: digital signal compared to the original analog signal. And again
Speaker 1: we're talking about digitally describing an electric current. At this point,
Speaker 1: we're not talking about describing the sound necessarily. We're describing
Speaker 1: the electric current that the transducer created after the sound
Speaker 1: went through the transducer. Now, if the sample rate of
Speaker 1: an A d C is too low, you get what's
Speaker 1: called alias sing. Now, this means that the digital signal
Speaker 1: will differ greatly from the original signal. Uh. And that
Speaker 1: means that you're not going to have a good representation
Speaker 1: of what was originally creating that signal in the first place,
Speaker 1: in this case, whatever the sound was. UH. So that
Speaker 1: that's what alias sing means in this context. Now, a
Speaker 1: A DOCK or d a C is a digital to
Speaker 1: audio converter, and it's basically the same thing we just
Speaker 1: talked about, but in reverse. The d a C takes
Speaker 1: digital information, which essentially is describing an analog signal an
Speaker 1: electric current of variable voltage. Then it produces that analog signal.
Speaker 1: The way it does again depends upon the type of
Speaker 1: d A C. Just as A d C s have
Speaker 1: different methodologies, so do d a C s. H. I
Speaker 1: might do an episode that goes into more detail, like
Speaker 1: I mentioned at the top of this episode, But honestly,
Speaker 1: once you really start diving in there, it gets incredibly
Speaker 1: technical very quickly. Generally speaking, we're talking about sophisticated circuit
Speaker 1: boards that are designed to convert digital to analog or
Speaker 1: vice versa, to switch between the data made up of
Speaker 1: zeros and ones and a continuous electric signal. And again,
Speaker 1: if there's interest, I'll go into more about how that works,
Speaker 1: but believe me, it gets really complicated, and without visual
Speaker 1: aids it's really hard to kind of get it across. Anyway,
Speaker 1: Now let's talk about audio files. Also, I should mention
Speaker 1: there's a ton of stuff I did not talk about, right,
Speaker 1: I didn't talk about multiplexing or anything like that, So
Speaker 1: there is a lot more to it than just the
Speaker 1: general information I'm giving anyway. Audio files. So, back in
Speaker 1: the day when c d s were fairly new, there
Speaker 1: were audio files who just despised digital media. The process
Speaker 1: us of converting an analog signal into a digital file
Speaker 1: and then back again to analog. Well, that represented a
Speaker 1: potential loss in quality, right, the playback experience might not
Speaker 1: be as vibrant. Audio files typically use words like warm
Speaker 1: or full to describe sound. These are words that are
Speaker 1: hard to quantify they are experiential, I guess, and they
Speaker 1: would lament that digitization removed some of those elements from recordings.
Speaker 1: The thing is, depending upon how you're digitally sampling a signal,
Speaker 1: some of that could be actually happening. You could be
Speaker 1: losing harmonics. And this isn't even touching on the issue
Speaker 1: that you start getting if you're if you're doing stuff
Speaker 1: like compression file compression in this sense. I'll talk about
Speaker 1: audio compression in a bit, but file compression can involve
Speaker 1: using what are called lossy formats. A lossy format discards
Speaker 1: part of a digital file that describe a signal, and
Speaker 1: typically the way it does this is that the encoding
Speaker 1: process is getting rid of information that it deems as
Speaker 1: being irrelevant. So let me explain that last bit. I
Speaker 1: did a full series of episodes about MP three's that
Speaker 1: goes into this into far more detail, but i'll give
Speaker 1: it down in dirty version for this episode. So, the
Speaker 1: MP three method of compressing a file takes a psycho
Speaker 1: acoustic approach in part when figuring out how to make
Speaker 1: an audio file size smaller, because raw audio files can
Speaker 1: be huge if you're really using a very high sample
Speaker 1: rate and a big bit depth. During your recording process,
Speaker 1: you're generating enormous files, right because the system is taking
Speaker 1: data many many many times, many thousands of times every
Speaker 1: second and using an enormous amount of information to try
Speaker 1: and describe that signal each time, every single snapshot. That's
Speaker 1: a lot of information and that isn't really convenient if
Speaker 1: you want to store that file on like an old
Speaker 1: MP three player. You know, if you remember those where
Speaker 1: you had to like in the old old days, you
Speaker 1: had to connect them physically to your computer. You would
Speaker 1: download or rip music and you would then send that
Speaker 1: music file to your device. These devices had very limited
Speaker 1: storage space on them, so you couldn't really hold a
Speaker 1: lot of raw audio. Like a single file might end
Speaker 1: up taking up the entire storage on your m P
Speaker 1: three player. And maybe you really like journeys Don't stop Believing,
Speaker 1: but you might want some other songs on there too.
Speaker 1: This is also more complicated if you want to do
Speaker 1: something like stream music. You don't want to have enormous
Speaker 1: files that would require like a gigabit Internet connection in
Speaker 1: order to be able to stream it, So you have
Speaker 1: to have a way to compress files down to sizes
Speaker 1: that are easier to handle well. The way the MP
Speaker 1: three algorithm does this is that once you set some
Speaker 1: general parameters, like you decide how compressed you want to
Speaker 1: make this file, essentially you're telling the MP three algorithm
Speaker 1: how hard it needs to go. When it's starting to
Speaker 1: cut stuff, well, then the algorithm begins to toss out
Speaker 1: data that, at least in theory, should not affect your
Speaker 1: experience when you listen back to the audio playback. So,
Speaker 1: for example, let's say you've got a sound file and
Speaker 1: in that sound file you have a very soft sound
Speaker 1: that immediately follows a very loud sound. So loud sound happens,
Speaker 1: soft sound happens immediately after that. Well, you wouldn't actually
Speaker 1: hear that really soft sound, and that's just because of
Speaker 1: how our ears work. The loud sound effectively masks the
Speaker 1: softer one, so it's almost like the soft one didn't
Speaker 1: exist at all. Well, if it's like the soft one
Speaker 1: didn't exist, then there's no reason to keep it right.
Speaker 1: If you couldn't hear it anyway, there's no reason that
Speaker 1: that should be in uh the file, right, So the
Speaker 1: algorithm effectively, through analyzing this data says, ah, that doesn't
Speaker 1: need to be in there. No one would hear it,
Speaker 1: so it tosses the data out. That's why it's a
Speaker 1: lossy file format. The same goes for frequencies that would
Speaker 1: be outside the range of human hearing. The logic is, well,
Speaker 1: you can't hear something that's at killer hurts, so we're
Speaker 1: just gonna get rid of anything that's occurring at that
Speaker 1: frequency because there's no reason to keep it. However, depending
Speaker 1: on how much you want to compress that file, those
Speaker 1: cuts can really start to affect the quality of the
Speaker 1: playback audio when you put it back through you know,
Speaker 1: a decode er and you get the audio on the
Speaker 1: other end. By the way, as I mentioned, file compression
Speaker 1: is not the same thing as audio compression. I'll explain
Speaker 1: what I mean by that, but first let's take one
Speaker 1: last break. Okay, before the break, I said that audio
Speaker 1: compression and file compression are two different things. It does
Speaker 1: get confusing, and I myself have been guilty of kind
Speaker 1: of interchanging the words or not clarifying enough while talking
Speaker 1: about compression and uh, thus I have been guilty of
Speaker 1: confusing it even more so. My apologies for that, but
Speaker 1: let's get to it. Audio compression refers to reducing the
Speaker 1: dynamic range of volume in a recording. Uh So, in
Speaker 1: other words, it's about reducing the volume distance between the
Speaker 1: softest sounds and the loudest sounds. Now, this can be
Speaker 1: really important for certain types of recording. I'll give you
Speaker 1: an example that I frequently run into that drives me nuts.
Speaker 1: And this happens a lot with like streaming media for me,
Speaker 1: so movies and television. Have you ever watched like an
Speaker 1: action movie where you can barely hear some of the dialogue,
Speaker 1: especially if people are speaking in like low voices and
Speaker 1: you know they're trying to be secretive or whatever. And
Speaker 1: then so you turn the volume up so that you
Speaker 1: can hear what people are saying. But then the next
Speaker 1: time something explodes, you're worried that you've just destroyed all
Speaker 1: your speakers, or maybe you've caused yourself permanent hearing damage.
Speaker 1: This happens to me all the time, where the softest
Speaker 1: sounds and the loudest sounds are so far apart that
Speaker 1: there's no comfortable volume. I can select where I can
Speaker 1: hear everything and not feel like one I'm missing out
Speaker 1: on some dialogue, or two my neighbors are going to
Speaker 1: come over and complain that I've got my volume turned
Speaker 1: up too loud. So compression in a case like that
Speaker 1: can narrow the gap between the softest parts and the
Speaker 1: loudest parts so that you can find that kind of
Speaker 1: comfortable volume where you can hear everything. However, going overboard
Speaker 1: with audio compression will reduce the dynamic range in a
Speaker 1: recorded piece of audio, and if you do that too much,
Speaker 1: it can make the audio sound flat and uninteresting, where
Speaker 1: everything is just coming out at exactly the same volume.
Speaker 1: If there's no real volume range, then your ears just
Speaker 1: kind of get tired of hearing everything played back at
Speaker 1: that same level. Some digital recordings really suffered from this
Speaker 1: kind of processing, Like there was an era of music
Speaker 1: where audio files in particular were really complaining that everything
Speaker 1: that was being laid down had so much compression in
Speaker 1: it that there was no real dynamic range and audio,
Speaker 1: and it just meant that the music wasn't as interesting,
Speaker 1: like there wasn't there wasn't enough variation, and it makes
Speaker 1: music kind of boring. Uh, it wouldn't matter if you
Speaker 1: had an analog pressing of a digital recording session, because
Speaker 1: analog does not magically fix the problems of the recording process.
Speaker 1: So if you're recording digitally, and then you make a
Speaker 1: vinyl record pressing of that digital recording. I mean, all
Speaker 1: that processing you did on the digital side, that's still
Speaker 1: going to be part of what ends up being recorded
Speaker 1: on the vinyl. It's it's not like vinyl suddenly cures
Speaker 1: all sins of digital. So even if you were to
Speaker 1: to go with analog audio media, you would still have
Speaker 1: the same problems that were introduced in the digital processing. Now,
Speaker 1: this does not mean that all digital to audio is
Speaker 1: inherently flawed. Even if we just look at the analog chain,
Speaker 1: we have to acknowledge that the process of recording in
Speaker 1: playback means, you know, you're taking pressure waves of the
Speaker 1: original sound, you pass them through a system that converts
Speaker 1: those pressure waves into an analog electric signal, and then
Speaker 1: you've got to reverse that process during playback, and stuff
Speaker 1: can happen along that pathway that could affect either the
Speaker 1: recording process or the playback process or both. So, in
Speaker 1: other words, analog does not necessarily mean better, because flaws
Speaker 1: can exist in the analog approach just as they can
Speaker 1: with the digital approach. And there are other elements as well,
Speaker 1: such as low level noise. Analog systems can introduce a
Speaker 1: low level noise into a signal. Digital avoids that. Now,
Speaker 1: that does not mean that digital is better, mind you,
Speaker 1: because there are other ways to reduce and eliminate noise
Speaker 1: and analog systems and digital can introduce other artifacts that
Speaker 1: didn't exist in the original signal, and then that comes
Speaker 1: across as like errors in your playback, Like you might
Speaker 1: hear some weird blip noise and think, what the heck
Speaker 1: was that, and it wasn't necessarily present in the original
Speaker 1: recording session, but was introduced as a digital artifact. This
Speaker 1: is just another example of how one format is not
Speaker 1: necessarily superior to the other. It depends on way too
Speaker 1: many other factors. They're just different. And honestly, I'm fairly
Speaker 1: confident that if you were to do a double blind test,
Speaker 1: and just in case you're unfamiliar with that term, double
Speaker 1: blind is a type of scientific test where neither the
Speaker 1: subject that's going through the test nor the person who
Speaker 1: is in charge of administering the test knows which version
Speaker 1: anyone is getting. So if you have a control group,
Speaker 1: the person administering the test doesn't know if that's a
Speaker 1: control group or if it's an actual test group. That
Speaker 1: they're testing at any given time. That way, the person
Speaker 1: administering the test does not give bias to the person
Speaker 1: who's experiencing the test. The thought is, if I know
Speaker 1: as an administrator, then I might give a tell to
Speaker 1: the test subject. Right. So let's say it's a double
Speaker 1: blind test and the audio files are going into a
Speaker 1: room and they're going to experience the same piece of
Speaker 1: audio recording, but it's over different systems. So like some
Speaker 1: of the pieces of the same stretch of audio are
Speaker 1: analog sources, some of them are digital sources. They might
Speaker 1: even include different like systems like premium systems, like super
Speaker 1: super high end systems that cost maybe upwards of hundreds
Speaker 1: of thousands of dollars, and maybe just on some that
Speaker 1: are really good systems, like you know, they're still expensive.
Speaker 1: Maybe it's a few thousand dollars, but they're not, you know,
Speaker 1: monumentally expensive. My bet is that most audio files would
Speaker 1: have trouble picking out which ones are analog systems versus
Speaker 1: digital systems unless there's some giveaway, like if you hear
Speaker 1: the scratch of a needle hitting record, then that's kind
Speaker 1: of a dead giveaway. But let's say you know you're
Speaker 1: you're talking about, like the highest of high ends. I
Speaker 1: don't think they would be able to tell the difference
Speaker 1: very easily. And that's because our approach to digital processing
Speaker 1: has become sophisticated enough that to our human ears, it's
Speaker 1: pretty close to an analog signal. And that you know. Also,
Speaker 1: I want to mention the returns on those high end
Speaker 1: audio equipment, like the differences that you start to see
Speaker 1: when you're really hitting that upper echelon of audio equipment.
Speaker 1: Some of those returns are so minor that after you
Speaker 1: reach a certain point, they are largely meaningless. Like like,
Speaker 1: as far as perception goes, you wouldn't be able to
Speaker 1: tell the difference. Uh, And for people like me, people
Speaker 1: who have had some hearing loss, it matters even less
Speaker 1: than that, right because like for me, like you could
Speaker 1: almost say, it's like I have an unsophisticated palette, Like
Speaker 1: you could serve me an amazing meal, but I'm not
Speaker 1: likely to notice it being any better than you know,
Speaker 1: a cheeseburger. But again, this is my hypothesis. I I
Speaker 1: believe this is probably true. It is entirely possible, and
Speaker 1: I admit this that if I actually were to conduct
Speaker 1: this kind of study, I might find that I'm totally
Speaker 1: wrong that the audio files are like no, that is
Speaker 1: clearly the premium, and maybe the differences are subtle, but
Speaker 1: maybe they're detectable. Right, It could be that I'm wrong
Speaker 1: about that. Uh. I just think that there gets to
Speaker 1: be a point where people start to buy into a philosophy,
Speaker 1: especially with audio files that isn't necessarily supportable by you know,
Speaker 1: quantifiable evidence. It becomes so subjective that once you remove
Speaker 1: the subjective element, like you remove the ability for them
Speaker 1: to know whether or not they're listening to their preferred
Speaker 1: set up, that it starts to disappear. Maybe I'm wrong
Speaker 1: about that. I don't think I am, But that's the
Speaker 1: overview of analog and digital and why you have to
Speaker 1: have the converters. As I said, to get into specifics
Speaker 1: would take more time, you know, talking about delta Sigma
Speaker 1: processing and that kind of stuff. But if you want it,
Speaker 1: let me know and I will try and put that
Speaker 1: episode together. It will just be far more niche oriented
Speaker 1: than even this one was. B It is a fascinating subject,
Speaker 1: like there's some really cool technology that goes into making
Speaker 1: this all work, and the fact that that technology does
Speaker 1: work and that it has become so sophisticated is why
Speaker 1: I feel pretty confident in saying that with a sufficiently
Speaker 1: good system, you wouldn't be able to tell the difference.
Speaker 1: But that's it for this episode. If you would like
Speaker 1: me to cover any kind of topic, whatever it might
Speaker 1: be in the tech world, let me know. The best
Speaker 1: way to get in touch is on Twitter. The handle
Speaker 1: for the show is tech Stuff h SW and I
Speaker 1: greatly appreciate it. I'm getting some wonderful suggestions. Really makes
Speaker 1: my job easier because I know exactly what people want
Speaker 1: to hear um. So yeah, reach out and let me
Speaker 1: know what you think and I'll talk to you again
Speaker 1: really soon. Tech Stuff is an I Heart Radio production.
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Speaker 1: to your favorite shows.