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Is the iPod Generation Going Deaf? 632

Posted by ScuttleMonkey
from the welcome-your-hearing-aid-dependant-overlords dept.
prozac79 writes "Ars Technica and Wired News are both running interesting articles on how personal music players are a major contributor [ArsTechnica] to early hearing loss [Wired]. According the ArsTechnica article, an increasing number of people are now living in "noisy" environments that is only made worse by blocking it out with even louder music. The article also suggests that listening to music for one hour a day is considered safe. So now you have a choice... go deaf early or go insane listening to your coworkers chatter."
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Is the iPod Generation Going Deaf?

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  • by Talondel (693866) on Wednesday September 14, 2005 @01:41AM (#13554746)
    Didn't I read this same story about Walkman's 20 years ago? And didn't they decide the effects were negligable? Oh yeah I did. Abstract from a study in 1987: Krahenbuhl D, Arnold W, Fried R, Chuden H. Investigations on 50 high school students showed that this group had been using the "Walkman" only 1.5 h. per day during the last 14 months. A comparison of the audiometric results obtained with these 50 "Walkman" users, with those of 20 age-related non-"Walkman" users, showed no statistically significant differences. The investigation further revealed that to avoid hearing loss, an upper threshold level of 93 dB (A) should not be exceeded for a daily "Walkman" user time of two hours. PMID: 3613781 [PubMed - indexed for MEDLINE]
  • by rm999 (775449) on Wednesday September 14, 2005 @02:04AM (#13554873)
    I just bought these headphones: http://www.amazon.com/exec/obidos/tg/detail/-/B000 065BP9/ [amazon.com]

    They offer really good sound isolation (I sat next to the engines in a loud airplane last month and when I wore them I heard almost nothing).

    They are a good alternative to sound cancellation - if you don't let sound in, you don't need to cancel it with iffy technology. Plus it costs less than 10% of the money and gives superb sound quality (not audiophile, but the best you can expect for less than a 100 imo).
  • by cbirkett (904502) on Wednesday September 14, 2005 @02:11AM (#13554901) Homepage
    I was going to suggest exactly the same thing. My er6is are a godsend in noisy environments. When I stick them in my ears, I can't even hear a person talking beside me. An added bonus is that because there's no background noise, you don't need to turn up the volume as much. Of course, there are cons, like the inability to hear warnings, phones, and such, but you have to take that into account when you decide to use them. I keep the phone where I can see it ringing, keep an eye on the receptionist when I'm waiting for an appointment, etc. They're basically like earplugs that can play music.

    Etymotic also makes sound attenuators for use when you actually want to be able to hear what's going on. They reduce sound by approximately 20dB in a fairly linear way, which is great for obnoxiously loud concerts, clubs, etc. They're pretty cheap, too.
  • by squidinkcalligraphy (558677) on Wednesday September 14, 2005 @02:29AM (#13554965)
    in-ear-canal phones like the shure and etymonics do just as good a job in reducing outside noise as the active cancelling ones, plus have much better quality drivers to boot (and don't require batteries). My Shure e2c's are better that any headphone I've ever tried, and the volume on my jukebox seldom goes above 20%, compared to a around 70-80% with normal earbuds. And they only cost about US$70. The next up in the range are supposed heaps better still, but at a cost (one, day, she will be mine, oh yes)
  • Re:Solution (Score:2, Informative)

    by hhghghghh (871641) on Wednesday September 14, 2005 @02:33AM (#13554980)
    I was gonna mod you up, but I'm gonna have to join in the rave, right here. I've got a pair of Koss The Plug headphones that I really like -- it takes some getting used to stuffing all that foam in your ear, but it isolates outside sound great. Not 44dB, but still impressive. Apparently sony [powerbookcentral.com] also have an affordable, and better-sounding, isolated headphone, which is surely on my list of stuff to get. I've tried Sony's active noise cancelling headphones, and the effect is amazing; you'd be standing next to a subway wagon speeding past hearing almost nothing. Kinda scary, even. Neatest thing is a switch to turn noise cancelling on or off so you can hear the effect (or perhaps switching noise cancelling "off" just turns on a noise generator ;-).

    I'd say, go for some sony plugs - they're really not bad, and you can spend as much or as little as you like. (I also like Sennheiser, for non-isolated/noise-cancelling headphones for everyday use, the low end stuff is great value for money, especially compared to low end crap from Philips).
  • by Anonymous Coward on Wednesday September 14, 2005 @02:46AM (#13555021)
    Seriously: I was born 1969 and clearly are part of the walkman generation, using one (OK, cheap copycats) from the mid 80s till the early 90s. Then I exposed my ears to techno parties :-P Whenever they check my hearing at the doctor or hospital they are surprised how good I hear considered my age.

    I'm a year older than you, and likewise my hearing is still intact. Doesn't do me much good though since I got tinnitus [ata.org] instead. Not in the eighties but about ten years later. There seems to be a correlation between the amount of noise you've been subjected to earlier and later development of tinnitus. If you experience "disco tinnitus" then you're at risk. You don't want to wake up one day still hearing it, belive me. I'd easily take a 15-25 dB hearing loss to get rid of the noise during the first 7 years I had it.

    And on the point of tinnitus, society has clearly gotten noiser with a corresponding rise in tinnitus in the past decades or so, e.g. many teenagers now make their tinnitus debut at the movies, something that wasn't heard of in the eighties. It's the leading cause of suicide in teenagers here in Sweden.

    If you've recently gotten it, don't do that though. It will get better, there will come a time when you'll think "If this was all I had to worry about, I would be happy".

  • by leifsa (665284) on Wednesday September 14, 2005 @02:48AM (#13555026)
    It really depends on your situation. Mine for example with a slight hearing disability on my right ear after a nasty accident as a kid left a wooshing sound, I really should avoid too high volumes not to make it worse. As always, use your senses so you dont end up with a constant ringing bell in your ear. I have friends with ringing ears and it's a pain for them especially at nights.
  • by Anonymous Coward on Wednesday September 14, 2005 @02:55AM (#13555054)
    The only way to reduce this to limit the exposure time your ears endure. Hearing loss is a fact of life for anyone who wear's headphones for an extended period at high decibel levels, whether it's an iPod, Walkman or whatever. Check the link.

    http://www.hearnet.com/at_risk/risk_aboutloss.shtm l [hearnet.com]

    From someone in the music industry, I cannot recommend noise cancelling phones or buds enough for someone who loves music and values their hearing. They are worth every penny and more. For the frequent concert goer or clubber, see an audiologist and get professional earplugs made. You won't sacrifice any sound quality and you'll preserve your hearing for future concerts and the rest of your life. It's one of the best investments you'll ever make.
  • by Bob9113 (14996) on Wednesday September 14, 2005 @03:01AM (#13555075) Homepage
    People will look at you funny, but earplugs with headphones is the right answer. You can eliminate all the background noise, and play the music at a level that (after passing through the earplugs) is safe. Foam earplugs are available at drugstores - 20 - 30 pairs for about 6 dollars. To really do it right, get a nice pair of circumaural headphones like Sennheisers.
  • by bombadier_beetle (871107) on Wednesday September 14, 2005 @03:19AM (#13555126)
    As a proud owner of a Rio Karma, I wanted to get the most out of that player's superior sound quality (take that, iPod!), so I picked up a pair of Etymotic ER-6 earplugs [etymotic.com]. They provide about 35 dB of sound isolation, and the sound quality is utterly amazing. I've never had to pump the volume on my Karma past 20% while using them - and when I'm listening to music with them, I can't hear the phone ring three feet away (another huge benefit).
  • by Dark Coder (66759) on Wednesday September 14, 2005 @04:06AM (#13555269)
    You do not want to exceed 95 dB, ever: EVER!

    Take it from a deaf person whose hearing loss is averaged as 64 dB at 20Hz down to 95 @ 8 KHz. That is the surveyed threshold for a lifelong usage of a hearing aid without losing ones remaining hearing (thus rendering such hearing useless).

    Hearings is not recoverable as the many tiny cilia hair nerves gets shortened at greater than 95 dB due to excessive POUNDING of the noise whipping these reed-like cilia back and forth (tearing or cutting off blood flows) as amplified by your middle ear bones and outer ear's ear drum.

    Protect your ears, take it from a deaf person. It is career threatening in your mid-life. No need to get another cow during your mid-life crisis.

    Cholear implant (CI) is a proven technology, but a bothersome hinderance to those late-deafened teens and adult as they did not grow up accustomed to these CI outfits. (Doable, but takes longer to get accustomed to these CI). CI is not a perfect replacement as you would get 32 channels (more later) spread across the sound spectrum but with GAPS in between. Computer/signal processors back-fills in these inter-channel gaps (not pleasant to a true classic music afficiandos).

    Keep it down... It might save your life.

    Don't get hit by a bus because you're IPODing. (interesting tidbits: 422 deaf people were killed by bus.)
  • by rklrkl (554527) on Wednesday September 14, 2005 @04:06AM (#13555272) Homepage
    I believe (though trying to find it on www.eu.int [eu.int] looks tricky !) that the EU has statutory maximum volume limits on audio devices where headphones can be attached (but I could be wrong on this). Mind you, I just bought a new MP3 player [mymemory.co.uk] that is "comfortable" volume in the 15-25 range, but it can go to ear-bleeding "40", which I suspect is way above the EU limits. Strange, though, because I have another player [mymemory.co.uk] that the same site sells and that's got a much lower maximum volume.
  • Re:1985 (Score:5, Informative)

    by cowbutt (21077) on Wednesday September 14, 2005 @04:20AM (#13555320) Journal
    i've gone to so many live shows (blisteringly loud metal) that i can't even listen to music loud anymore - it's my own fault, but now i wear earplugs for shows simply because it actually hurts to listen to loud music.

    The turning point for me was seeing At the Gates and a couple of other bands at a small pub in 1997 (and, I admit it, seeing a photo of Alx Hellid of Entombed wearing plugs on-stage). Before then, the longest periods of tinnitus I'd experienced were 2.5 days after seeing bands (e.g. Anthrax) in larger venues in the late 80s. After this gig, though, I experienced tinnitus for 4 days. By the end, I was promising myself that if it went, I'd wear plugs at gigs in future. The tinnitus did pass, and I've kept that promise (with the exception of "treating myself" for favourite songs or short sets!)

    Similarly, once I started jamming in a band earlier this year, I got fed up with the tinnitus and general fatigue induced by the drummer's brass, and quickly picked up a pair of Elacin ER-20 [hearingprotection.co.uk] plugs. I can thoroughly recommend these for use by musicians and concert-goers as the attenuation (-20dB, or 75% of the energy) is fairly flat across the audio spectrum. If you've previously tried foam plugs, or cotton wool, and didn't get on with either, try these and a reckon you'll be pleasantly surprised.

    One note though; I saw Cradle of Filth and Mendeed recently, and despite wearing my ER-20s throughout both sets, I still had some minor post-gig tinnitus afterwards that was gone by morning!

  • by Hackeron (704093) on Wednesday September 14, 2005 @04:20AM (#13555325) Journal
    http://www.shurestore.com/earphones/eseries_e5c.ht ml [shurestore.com] - Its all in the name of good health, right?

    But seriously, I had mine for about 6 months now and I have to say the isolation is incredible. Baby screaming at the DVLA? no problem. Construction and train noises are also easily blocked out. The London Underground is a good test because its *very* loud - you cant hold a conversation screaming at the top of your lungs there. Here the isolation isnt enough, but all you hear is a faint windy sort of noise, which is fine.
  • European ipods (Score:3, Informative)

    by BlightThePower (663950) on Wednesday September 14, 2005 @04:33AM (#13555359)
    are locked to a maximum "safe" volume. You can unlock them if you want but I've never felt the need myself. I suppose its American-libertarian to let you deafen yourself when you damn well want to be deafened or something.
  • Re:1985 (Score:2, Informative)

    by Anonymous Coward on Wednesday September 14, 2005 @04:57AM (#13555434)
    I used to have tinnitus after loud shows. It would last a day, two days, sometimes 3-4 days. It always went away. Then one time it didn't. After one show it became permanent. I hear ringing constantly now, 24/7, no matter what I'm doing.

    I protect my hearing carefully now, but the tinnitus and hearing damage will never go away. There is no cure, and there likely won't be in my lifetime. There is some promising research on nerve cell regeneration, but I doubt it'll result in an effective therapy for a long time.

    Bottom line: Wear those earplugs. Once it's gone, it's gone.
  • Re:Heh, the irony (Score:5, Informative)

    by hcdejong (561314) <hobbes@xmsnet . n l> on Wednesday September 14, 2005 @05:33AM (#13555548)
    Both of these responses are exactly the things that XYZ-philes always say.

    That doesn't make them untrue. This isn't painting-the-edges-of-a-CD audiophile nonsense, it's verifiable through simple means.

    That 'niche at the upper end of the mainstream' is occupied by companies like Denon, Onkyo and Marantz, not Bose.

    Have you ever tried comparing a Bose system with anything else? You know, actually do listening tests?
  • Re:1985 (Score:5, Informative)

    by EtherealStrife (724374) on Wednesday September 14, 2005 @05:33AM (#13555550)
    Ditto. I can second the suggestion. I'm in my 20's and I already have permanent -- and uncorrectable -- hearing damage. You can't imagine how frustrating it is walking around 24/7 with a constant background static buzzing away...until you have it yourself. And when I'm surrounded by complete silence (soundproof rooms/studios) the sound is emphasized, and becomes deafening. And since it's sensory damage, white noise doesn't do squat.

    They may look lame or uncool, but the alternative to wearing earplugs is much much worse.

  • Re:1985 (Score:5, Informative)

    by Anonymous Coward on Wednesday September 14, 2005 @05:51AM (#13555615)
    "Similarly, once I started jamming in a band earlier this year, I got fed up with the tinnitus and general fatigue induced by the drummer's brass, and quickly picked up a pair of Elacin ER-20 plugs"

    Beyond just passive plugs, have you thought about picking up honest to god in ear monitors?

    They take a little getting use to, but they work pretty well. The last band I was working with was a grammy nominated r&b group and with a dozen people on stage with brass and other instrumentation, it was as loud as any death metal band I'd ever worked with. Anywho, I started taking a pair of Shure in-ears with me and having the monitor guy give me a nice custom mix to my remote and this meant not only did I have near isolation, but I only needed to hear enough to keep my parts in line.

    A good pair of in-ears will isolate everything enough that you can listen at a much lower volume than you would have normally (this is especially true if you get the earpieces custom molded to further isolate). I prefer the Shure's, but there are a few others that are professional range and work for these applications.

    Anywho, posting this anonymously because slashdot don't like anyone that has made money through RIAA means and it would taint my future posts as a geek :-) If you have any questions about these, ask and I'll try to respond back though.
  • by Avumede (111087) on Wednesday September 14, 2005 @05:51AM (#13555617) Homepage
    I had the same problem. Try using canalphones. It lets you block out the outside noise, so you can maintain a low volume.
  • by labnet (457441) on Wednesday September 14, 2005 @06:54AM (#13555837)
    I do sound engineering, and you need to be 6-12dB above ambient noise to hear something clearly. Thus if you are in traffic of 95dB and you headphones cut out say 5dB, you will still need around 100dB. This could be damaging. See the tables below.

    Environmental Noise
    Weakest sound heard 0dB
    Normal conversation (3-5') 60-70dB
    City Traffic (inside car) 85dB
    Train whistle at 500' 90dB
    Subway train at 200' 95dB
    Level at which sustained exposure may result in hearing loss 90 - 95dB
    Power mower 107dB
    Power saw 110dB
    Pain begins 125dB
    Pneumatic riveter at 4' 125dB
    Jet engine at 100' 140dB
    Death of hearing tissue 180dB
    Loudest sound possible 194dB

    OSHA Daily Permissible Noise Level Exposure
    Hours per day Sound level
    8h 90dB
    6h 92dB
    4h 95dB
    3h 97dB
    2h 100dB
    1.5h 102dB
    1h 105dB .5h 110dB .25h 115dB

    Perceptions of Increases in Decibel Level
    Imperceptible Change 1dB
      Barely Perceptible Change 3dB
    Clearly Noticeable Change 5dB
    About Twice as Loud 10dB
    About Four Times as Loud 20dB

    Sound Levels of Music
    Normal piano practice 60 -70dB
    Fortissimo Singer, 3' 70dB
    Chamber music, small auditorium 75 - 85dB
    Piano Fortissimo 84 - 103dB
    Violin 82 - 92dB
    Cello 85 -111dB
    Oboe 95-112dB
    Flute 92 -103dB
    Piccolo 90 -106dB
    Clarinet 85 - 114dB
    French horn 90 - 106dB
    Trombone 85 - 114dB
    Tympani & bass drum 106dB
    Walkman on 5/10 94dB
    Symphonic music peak 120 - 137dB
    Amplifier rock, 4-6' 120dB
    Rock music peak 150dB
  • Re:Solution (Score:5, Informative)

    by fireboy1919 (257783) <rustyp@freeshell.COBOLorg minus language> on Wednesday September 14, 2005 @06:54AM (#13555838) Homepage Journal
    First of all, I'd like to say IANAA, IAAST (I am not an audiophile, I am a sound technician).

    No. They fail to isolate the low frequencies.

    Those go straight through something like a pair of earphones.

    However, active noise cancelling headphones (which in-ear 'phones are not ever, despite the GP's claim) can help out in cancelling the lows.

    Ear covering headphones (cans) have another problem in that the speakers themselves are not suspended, which causes problems with the high end getting absorbed by things that aren't your ears (causing strange nonlinearies).

    The big problem that in-ear headphones solve is in sound reproduction. Within the human range of hearing, most in-ear headphones claim to be able to reproduce any frequency without any nonlinearies (I haven't actually tried it myself, however I can point you to studies that test frequency response that confirm that they're much better than anything else). This is possible simply because the tiny, tiny elements don't have to produce much vibration to do their job, so the inertia of the speaker element becomes negligible, and because there's nothing else to get in the way of absorbing the sound besides your ear.
  • Re:Solution (Score:1, Informative)

    by Anonymous Coward on Wednesday September 14, 2005 @07:16AM (#13555951)
    I have had two generations of the Sony in-ear noise canceling phones. Neither has been able to cut the wideband noise from a subway (certainly not the howl of steel wheels and third-rail contact paddles). They are OK on commercial airlines but the claims are less than 10 dB reduction and I believe it.

    The effect on big airplanes is to reduce the rumble and low-mid roar a bit, such that I actually hear passenger conversations more clearly (when not playing any music). The downside is a very noticeable hiss which I gather is the cancellation error from slight phase problems and a system not calibrated to my own ear canal.

    The most annoying thing for me is the bone-conduction of low frequency noise on airplanes. I'll be resting away and slightly change the way my head is resting on the headrest and suddenly get a much worse noise floor creeping in right when I tried to sleep.

    Now I am wondering how much different the ER4 passive noise blocking experience really is... not sure I want to pop $300 on another experiment though.
  • by barzok (26681) on Wednesday September 14, 2005 @07:18AM (#13555968)
    The wattage doesn't matter. It's the decibels and proximity to the ear. Those iPod earbuds aren't anywhere near 6 watts, let alone 60 watts, yet they'll do plenty of damage.
  • by Mark_in_Brazil (537925) on Wednesday September 14, 2005 @07:52AM (#13556172)
    I got a 30GB 4G iPod ("The iPod Formerly Known As Photo") recently. A friend who works at Apple also recommended the ER6is, and I ended up getting a set of those too.
    The safety concerns are real. I probably wouldn't use them biking or around outside in a city, because you really can't hear what's going on around you. But on commercial airline flights, they are amazing. It can actually be startling to remove the earphones mid-flight and hear how loud the engines are. What's really weird is that you can indeed listen to your music at a volume that would be completely drowned out by the ambient noise without the isolating earphones.
    As mentioned in the parent and grandparent posts, Because of the noise isolation, you don't have to turn up the volume a lot. I've heard a few people complaining about the bass response, but I attribute this to two effects. First, many people are used to listening to music in a way that would be appropriate for those ridiculous cars with the monster sound systems whose bass you can hear from a distance of several km. But even more important, I think the people who complain about the ER6i bass haven't properly inserted the 'phones into their ears. I believe this is a common problem. I've seen it mentioned in a few reviews of the ER6is, and Etymotic Research is even including a slip of yellow paper in the ER6i packaging now with the following message:
    IMPORTANT

    For Best results:

    Be sure to obtain a good seal.
    Without it, you will not have an optimal bass response.

    In some cases, slightly moistening the white eartips will help improve the seal in your ear canals.
    So if you're researching ER6i earphones (and possibly other noise isolating earphones) online, and you read reviews saying they have "no bass" or something similar, keep this in mind.
    Etymotic even makes optional smaller and larger eartips to allow for the correct placement and seal in ears that the standard eartips don't fit just right.
    I do recognize that bass may be in the ear of the beholder, so YMMV. It's best if you can find somebody you trust and ask that person's opinion. I was fortunate to have the ER6i earphones recommended to me by somebody whose opinion I've come to trust, and I've been more than satisfied with them.
  • Re:Heh, the irony (Score:2, Informative)

    by Vr6dub (813447) on Wednesday September 14, 2005 @08:09AM (#13556306)
    As for you complaints about the Lifestyles system, you're obviously not the target audience. Take for example my Mother. She thinks they're cute and really likes that she can hide the speakers amongst all her nic-nacs. To be honest, I don't blame her. I'm not to familiar with all the available "micro" systems but Bose is the one of the few manufacturers that I've seen in brick and mortar stores. On a side note, I have a pair of my Dad's old 901's and they still kick ass after all these years (almost 20!!). Pair them with a sub and I have been perfectly happy. Although, IAMNAAudiophile.
  • Earplugs (Score:4, Informative)

    by Crazy Man on Fire (153457) on Wednesday September 14, 2005 @08:16AM (#13556362) Homepage
    I'm a DJ and in addition to my shows, I frequently go out to clubs to hear other DJs. I had similar experiences with ringing ears for days after a loud show. I tried foam earplugs, but they made everything sound terrible. I finally broke down and got custom "musician's" earplugs. Mine are Westone [westone.com] ES49 [westone.com]. I've never been happier! These things keep the sound quality almost the same, just reduce the volume (mine have 15db filters in them).
  • by Thurn und Taxis (411165) on Wednesday September 14, 2005 @08:36AM (#13556513) Homepage
    You're absolutely right that noise-reducing headphones most likely help rather than hurt. However, your statement about hearing loss being caused by high-frequency sound is incorrect. Loud low-frequency sound is much worse than loud high-frequency sound, because the loud sound has to travel along the entire length of the cochlea to reach its intended destination, and it causes damage along the way. The reason you lose high-frequency hearing first is that the high-frequency region of the cochlea is closest to where the sound comes in, so that every loud sound that hits your ears passes by that region and causes damage.

    Preventing significant hearing loss is easy - don't blast music, and give your ears a rest once in a while. It's kind of like not staring into the sun all day, but for your ears.
  • by Phisbut (761268) on Wednesday September 14, 2005 @09:42AM (#13557120)
    Hearing loss is caused by a number of factors; yes, loud sound can do it, but high_volume != high_frequency. Where did you unearth this particular piece of mis-information??

    Take a course in biology and you'll learn that high-frequency noises are indeed related to loss of hearing.

    The cochlea (inner ear) uses tiny "hair cells" to "catch" sounds (vibrations) and transform them into a signal that the auditory nerve can get to the brain. Different lengths of hair cells catch different wavelength of sound. Higher frequency noises (shorter wavelength) are caught by the shorter hair cells.
    Those cells being shorter (thus smaller), they are somehow more fragile than their longer counterparts, so they are the first ones to die with age / hearing of loud noises.
    Loss of hearing happens usually with the higher-frequency noises first, because of the reason stated above. This is the reason why old people have a hard time understanding what women say (higher-pitched voice) while being able to hear men much better (lower-pitched voice, higher chance that hair-cells for that frequency are still alive).

    High-frequency noises will always be the firsts to go when going partially deaf. They all go eventually though. Higher wave amplitude (volume) will make that happen sooner. Canceling out low and mid frequency noises will keep some hair cells from being hurt, but if the high-frequency sounds still go through, short hair cells still get hurt.

    Linky [reference.com]
    Linky [gsu.edu]
    Linky [www.vimm.it]

  • by Thurn und Taxis (411165) on Wednesday September 14, 2005 @10:17AM (#13557439) Homepage
    Wrong.

    The cochlea is a waveguide - incoming sounds launch a wave along the basilar membrane. This wave is dispersive, meaning that at a given location, low frequency energy travels more quickly than high frequency energy. For energy at a given frequency, the wave slows down as it travels until it reaches a "characteristic place". At the same time, the amplitude of vibration increases. The characteristic place is defined as the location where the amplitude of vibration peaks; for a given location, the frequency that causes the largest vibration is called the "best frequency" for that place. At the best frequency, the cochlea is locally resonant, and energy is shunted through the basilar membrane. As a result, the energy at a given frequency does not propagate significantly beyond the characteristic place (this is equivalent to saying that the wave speed decreases to zero near the characteristic place).

    The cochlea is tonotopically organized, so that more basal locations (near where the stapes inserts) have high best frequencies, and the best frequency decreases systematically with position as you move apically. As a consequence, high-frequency sound energy that enters the cochlea is shunted through the basilar membrane at a basal location, and does not propagate further into the cochlea. Low frequency energy, in contrast, propagates as a wave along the basilar membrane to the apical region of the cochlea. In other words, high-frequency sounds only vibrate the most basal part of the cochlea, whereas low-frequency sounds vibrate the entire cochlea.

    For more information on the cochlear traveling wave, read the classic papers by Georg von Bekesy, who won the Nobel prize for discovering it. You might also want to look at some of the early computational models by Zwislocki and/or de Boer. For a more introductory description, I recommend chapter 5 of Geisler's "From Sound To Synapse", or Patuzzi's chapter in the book "The Cochlea".
  • Re:Probably not (Score:2, Informative)

    by Transcendent (204992) on Wednesday September 14, 2005 @10:54AM (#13557832)
    The energy used is simply the energy required to create the "cancelling" noise, which is electrical and mechanical energy (~=heat).

    The "cancelling" noise is basically a phase inverted replica of the incoming noise. It's like total destructive interference on the sound... as much as possible anyway.
  • by TeknoHog (164938) on Wednesday September 14, 2005 @01:35PM (#13559352) Homepage Journal
    Simple noise cancellation works by taking the inverse of the 'noise' signal. This can be done with simple analogue circuits, there's no need to analyze the noise in any way. This doesn't care about any details about the signal, so persistent noises are cancelled just as well as sudden ones.

The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka!" (I found it!) but "That's funny ..." -- Isaac Asimov

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