1
00:00:00,520 --> 00:00:03,800
Speaker 1: Welcome to Brainstuff from how stuff works dot com where

2
00:00:03,840 --> 00:00:14,960
Speaker 1: smart Happens. Hi Am Marshall Brain with today's question, why

3
00:00:15,000 --> 00:00:18,080
Speaker 1: can you hear the ocean when holding a seashell up

4
00:00:18,120 --> 00:00:21,360
Speaker 1: to your ear? Do you remember trying this as a kid,

5
00:00:21,720 --> 00:00:24,560
Speaker 1: holding one of the seashells you grabbed as a souvenir

6
00:00:24,800 --> 00:00:27,440
Speaker 1: up to your ear. It seems like no matter how

7
00:00:27,520 --> 00:00:30,360
Speaker 1: far away from the ocean you are, you can still

8
00:00:30,400 --> 00:00:33,000
Speaker 1: hold a seashell up to your ear and hear the

9
00:00:33,080 --> 00:00:36,080
Speaker 1: roar of the waves rolling on to the shore. The

10
00:00:36,120 --> 00:00:39,720
Speaker 1: best shells for producing this sound are the large spiral

11
00:00:39,840 --> 00:00:43,720
Speaker 1: conch cells. Some people have suggested that the sound you

12
00:00:43,760 --> 00:00:46,720
Speaker 1: hear from the seashell is the echoing of your blood

13
00:00:46,840 --> 00:00:49,879
Speaker 1: rushing through the blood vessels of your ear. That is

14
00:00:49,920 --> 00:00:52,640
Speaker 1: not the case. If that were true, then the sound

15
00:00:52,680 --> 00:00:58,720
Speaker 1: would intensify after exercising, since your blood races faster after exercising. However,

16
00:00:58,800 --> 00:01:02,800
Speaker 1: the sound is the same even after exercising. Others say

17
00:01:02,840 --> 00:01:05,840
Speaker 1: that the wooshing sound inside the shell is generated by

18
00:01:06,000 --> 00:01:09,520
Speaker 1: air flowing through the shell. Air flowing through the shell

19
00:01:09,600 --> 00:01:13,039
Speaker 1: and out creates a noise. You'll notice that the sound

20
00:01:13,120 --> 00:01:15,840
Speaker 1: is louder when you lift the shell slightly away from

21
00:01:15,880 --> 00:01:17,920
Speaker 1: your ear than it is when the shell is right

22
00:01:17,959 --> 00:01:20,960
Speaker 1: up next to your head. However, this theory doesn't hold

23
00:01:21,080 --> 00:01:24,600
Speaker 1: true in a soundproof room. In a soundproof room, there's

24
00:01:24,680 --> 00:01:28,080
Speaker 1: still air, but when you hold the seashell to your ear,

25
00:01:28,160 --> 00:01:32,160
Speaker 1: there's no sound. The most likely explanation for the wave

26
00:01:32,240 --> 00:01:36,480
Speaker 1: like noise is ambient noise from around you. The seashell

27
00:01:36,560 --> 00:01:40,560
Speaker 1: that you're holding just slightly above your ear captures this noise,

28
00:01:40,880 --> 00:01:44,640
Speaker 1: which resonates inside the shell. The size and shape of

29
00:01:44,680 --> 00:01:47,600
Speaker 1: the shell therefore has some effect on the sound you hear.

30
00:01:48,240 --> 00:01:53,480
Speaker 1: Different shells sound different because different shells accentuate different frequencies.

31
00:01:54,040 --> 00:01:56,520
Speaker 1: You don't even need a seashell to hear the noise.

32
00:01:56,840 --> 00:02:00,440
Speaker 1: You can produce the same ocean sound using an empty cup,

33
00:02:00,880 --> 00:02:03,760
Speaker 1: or even by cupping your hand over your own ear.

34
00:02:04,400 --> 00:02:06,680
Speaker 1: Go ahead and try it and vary the distance at

35
00:02:06,720 --> 00:02:10,040
Speaker 1: which you place the cup near your ear. The level

36
00:02:10,040 --> 00:02:12,920
Speaker 1: of the sound will vary depending on the angle and

37
00:02:13,120 --> 00:02:17,359
Speaker 1: distance the cup is from your ear. Noise from outside

38
00:02:17,400 --> 00:02:20,520
Speaker 1: the shell can change the intensity of the sound you

39
00:02:20,639 --> 00:02:23,800
Speaker 1: hear inside the shell. You can look at the shell

40
00:02:23,880 --> 00:02:27,440
Speaker 1: as a resonating chamber. When the sound from outside enters

41
00:02:27,480 --> 00:02:31,000
Speaker 1: the shell, it bounces around, thus creating an audible noise.

42
00:02:31,480 --> 00:02:34,320
Speaker 1: So the louder the environment you're in, the louder the

43
00:02:34,360 --> 00:02:39,160
Speaker 1: ocean like sound will be for more illness and thousands

44
00:02:39,160 --> 00:02:41,760
Speaker 1: of other topics. Is that how stuff works dot Com

45
00:02:41,800 --> 00:02:43,680
Speaker 1: and don't forget to check out the brain stuff blog

46
00:02:43,760 --> 00:02:45,920
Speaker 1: on the house stuff works dot com home page. You

47
00:02:45,919 --> 00:02:48,880
Speaker 1: can also follow brain stuff on Facebook or Twitter at

48
00:02:48,880 --> 00:02:50,320
Speaker 1: brain Stuff hs W