1
00:00:02,040 --> 00:00:07,240
Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,

2
00:00:07,280 --> 00:00:10,200
Speaker 1: I'm Lauren Vogelbaum, and today's episode is another classic from

3
00:00:10,200 --> 00:00:13,280
Speaker 1: our former host, Christian Sagar. Our question of the day

4
00:00:13,440 --> 00:00:16,520
Speaker 1: is a little morbid and hopefully not pressing to anyone listening,

5
00:00:16,720 --> 00:00:20,800
Speaker 1: but interesting. Nonetheless, if a noise was loud enough, could

6
00:00:20,800 --> 00:00:28,880
Speaker 1: it straight up kill you? Hey, I'm Christian Sagar, and

7
00:00:28,960 --> 00:00:31,800
Speaker 1: this is brain Stuff. If you're standing next to a

8
00:00:31,920 --> 00:00:35,800
Speaker 1: jet during takeoff, your ear drums will probably burst. Same

9
00:00:35,800 --> 00:00:38,400
Speaker 1: thing happens when you fire a twelve gage shotgun right

10
00:00:38,400 --> 00:00:42,120
Speaker 1: next to your ear. When we're exposed to exceptionally loud noises,

11
00:00:42,440 --> 00:00:46,080
Speaker 1: something called the stereo cilia in our ears gets damaged.

12
00:00:46,560 --> 00:00:49,879
Speaker 1: This causes our ears to mistakenly send signals to our

13
00:00:49,920 --> 00:00:55,000
Speaker 1: auditory nerve cells. The resulting ghostly reverberations are what we

14
00:00:55,160 --> 00:00:59,080
Speaker 1: call ringing ear. Many of you have probably experienced this,

15
00:00:59,320 --> 00:01:02,720
Speaker 1: possibly for going to a really loud concert. The technical

16
00:01:02,800 --> 00:01:06,399
Speaker 1: term for it is tenitis, and it's usually temporary unless

17
00:01:06,440 --> 00:01:10,240
Speaker 1: you repeatedly damage your ears with loud noises. Then it

18
00:01:10,319 --> 00:01:14,000
Speaker 1: develops into chronic tenitis, where you hear that dull ringing

19
00:01:14,120 --> 00:01:17,720
Speaker 1: for the rest of your life and that's nothing compared

20
00:01:17,720 --> 00:01:20,679
Speaker 1: to what really loud noise can do to you. Noise

21
00:01:20,920 --> 00:01:25,600
Speaker 1: hates you, and noise can kill you. See, sound travels

22
00:01:25,600 --> 00:01:29,119
Speaker 1: in waves that enter our ear canals. These waves make

23
00:01:29,160 --> 00:01:32,200
Speaker 1: our ear drums vibrate, and if they're too strong, they

24
00:01:32,240 --> 00:01:35,120
Speaker 1: can snap the hair cells inside, and if these hair

25
00:01:35,160 --> 00:01:38,640
Speaker 1: cells die, they can never grow back. To avoid this,

26
00:01:38,880 --> 00:01:42,360
Speaker 1: we use units called decibels to measure the power of sound.

27
00:01:42,800 --> 00:01:45,920
Speaker 1: Anything below eighty five decibels is thought to be safe.

28
00:01:46,280 --> 00:01:49,400
Speaker 1: At a hundred and fifty decibels, your ear drums burst

29
00:01:49,800 --> 00:01:52,600
Speaker 1: like with the jet or the shotgun, and at two

30
00:01:52,680 --> 00:01:56,800
Speaker 1: hundred decibels, your lungs will rupture and likely kill you.

31
00:01:57,360 --> 00:02:00,560
Speaker 1: That's right. The threshold for death by sound is somewhere

32
00:02:00,640 --> 00:02:04,320
Speaker 1: between a hundred and eighty five and two hundred decibels.

33
00:02:04,840 --> 00:02:07,960
Speaker 1: What happens is the sound causes an air embolism within

34
00:02:08,000 --> 00:02:10,440
Speaker 1: your lungs that can travel to your heart and kill

35
00:02:10,520 --> 00:02:13,800
Speaker 1: you dead. That is, if your lungs don't burst first

36
00:02:13,840 --> 00:02:17,480
Speaker 1: from the increased air pressure caused by acoustic energy. This

37
00:02:17,520 --> 00:02:20,960
Speaker 1: has happened during wars when high energy impulse noise from

38
00:02:21,000 --> 00:02:26,240
Speaker 1: explosions causes something called blast over pressure. It leaves no

39
00:02:26,400 --> 00:02:30,640
Speaker 1: external injuries, but damages organs like your ears, lungs, and

40
00:02:30,680 --> 00:02:35,600
Speaker 1: gastro intestinal tract. Now, acoustic weapons are actually being developed,

41
00:02:35,800 --> 00:02:39,520
Speaker 1: but usually there for non lethal purposes. There's been talk

42
00:02:39,600 --> 00:02:43,520
Speaker 1: of acoustic bullets to burst ear drums, incapacitate a target,

43
00:02:43,800 --> 00:02:47,880
Speaker 1: or even kill them. Others claim that an infrasound generator

44
00:02:47,919 --> 00:02:51,840
Speaker 1: could also be lethal, but there's been little practical evidence

45
00:02:51,880 --> 00:02:55,720
Speaker 1: of such weapons so far. The closest we've seen is

46
00:02:55,760 --> 00:02:59,440
Speaker 1: a long range acoustic hailing device developed by the l

47
00:02:59,520 --> 00:03:02,640
Speaker 1: RAD co Operation, which can cause hearing damage from up

48
00:03:02,639 --> 00:03:06,799
Speaker 1: to fifty feet or fifteen point two four meters away.

49
00:03:07,200 --> 00:03:10,840
Speaker 1: Some shipping companies have started using these devices as seaborn

50
00:03:10,960 --> 00:03:15,200
Speaker 1: defense against pirates. There is one device, however, that could

51
00:03:15,240 --> 00:03:18,960
Speaker 1: most definitely kill you with sound. It's not a weapon,

52
00:03:19,240 --> 00:03:22,760
Speaker 1: but the European Space Agency has developed a huge air

53
00:03:22,800 --> 00:03:26,760
Speaker 1: horn that they used to test satellites and spacecraft, using

54
00:03:26,840 --> 00:03:29,600
Speaker 1: nitrogen gas to produce sounds up to one hundred and

55
00:03:29,639 --> 00:03:33,080
Speaker 1: fifty four decibels. They blast objects to make sure they

56
00:03:33,120 --> 00:03:36,440
Speaker 1: can withstand the noise of a rocket launching. The e

57
00:03:36,640 --> 00:03:39,680
Speaker 1: s A themselves are so concerned about how lethal this

58
00:03:39,760 --> 00:03:43,840
Speaker 1: horn is they've surrounded it with half meter thick walls

59
00:03:43,840 --> 00:03:48,200
Speaker 1: made of steel reinforced concrete coated with an epoxy resin

60
00:03:48,480 --> 00:03:53,280
Speaker 1: to reflect noise back into its chamber. But Christian, you're asking,

61
00:03:53,320 --> 00:03:56,160
Speaker 1: didn't you just say that the threshold for death is

62
00:03:56,200 --> 00:03:59,760
Speaker 1: between one hundred and eighty five and two hundred decibels.

63
00:03:59,800 --> 00:04:02,600
Speaker 1: It's true, I did, But the e s A believe

64
00:04:02,680 --> 00:04:06,160
Speaker 1: that prolonged exposure to the one and fifty four decibel

65
00:04:06,240 --> 00:04:10,000
Speaker 1: horn will kill you as well, probably rupturing your ear drums,

66
00:04:10,240 --> 00:04:13,440
Speaker 1: vibrating your eyeballs, and destroying you from the inside out.

67
00:04:13,880 --> 00:04:19,679
Speaker 1: If you're not dead, you'll probably wish you were. Today's

68
00:04:19,680 --> 00:04:22,360
Speaker 1: episode was written by Christian and produced by Tyler Klang.

69
00:04:22,560 --> 00:04:24,920
Speaker 1: If you miss Mr Sager, check out his pop culture

70
00:04:24,960 --> 00:04:28,960
Speaker 1: podcast super Context, available wherever you get your podcasts, and

71
00:04:29,080 --> 00:04:31,400
Speaker 1: of course, for more on this and lots of other topics,

72
00:04:31,480 --> 00:04:45,000
Speaker 1: visit our home planet, astu works dot com.