The subject surfaced in a recent World Forum of Acoustic Ecology posting. The charge I get from highly stimulating WFAE postings often lasts for days as this one did and I sometimes use that charge to articulate my thoughts on the particular posting and closely related matters. This page collects some of my thoughts on "loud music & hearing loss" and related matters. What follows immediately is the stimulus - Dr. Karlow´s original posting (creative spellings included) written in response to an earlier posting by Gary Ferrington describing his experience of trying to come to terms with the sound in his 10th floor apartment coming to him from a U2 concert taking place 3 miles away from him.
Date: Wed, 14 May 1997 12:39:00 -0700
From: ekarlow@LaSierra.edu (Ed Karlow)
Subject: loud music & hearing loss
The recent exchanges in this forum regarding the U2 concert in Eugene, Oregon which Gary Ferrington described reminded me to post the following reference:
"Hearing Loss & Music" by Ken Dibble in Journal of the Audio Engineering Society, vol 43, No. 4, 1995 April, pp. 251-266.
He summarizes studies of sound induced hearing loss spanning some 25 years from the UK and the USA. It's well worth the trouble to get a copy at $5.00 US from Audio Engineering Society, 60 East 42nd Street, New York, NY 10165-2520 USA.
Here are some salient quotes from his paper:
"...It is my view that there must be a difference between the NIHL [noise induced hearing loss] associated with exposure to loud music and that associated with industry.
"I'm not for one moment suggesting that exposure to loud music will not be ultimately harmful or that it will not lead to hearing impairment. If the playback levels are too high, and the accumulated duration of exporsure too long, it almost certainly will result in NIHL.
"It does however seem that research has failed to lend substance to the belief that all those involved with rock music or discotheques will be deaf by the time they reach the age of 30..." (page 251)
Quoting from a study by J. J. Knight in 1992 he states:
"Reporducing systems for music used over the past 30 years have a capability of creating sound levels greatly in excess of agreed limits for industrial noise. Many articles in the popular press and scientific journals have warned of the consequent danger to hearing.
"However, few patients attending the Royal National Throat Nose & Ear Hospital [in London] during this period have more than minimal permanent changes in their hearing sensitivity attributable to these noise sources, among an approximate 10,000 new cases of deafness seen each year.
"In the context of pop music the resulting hearing loss is *less prevalent* than nodules on the larynx of vocal performers." (emphsis mine)
Ken sums up by saying:
"The weight of evidence suggests that music as a cause of noise induced hearing loss is nowhere near as damaging as what might be described as conventional industrial noise, or as prevalent as many would have us believe... There is also a body of evidence to support the oft expressed notion that sound which is pleasing, and therefore less stressful, may also be less damaging medically." (page 264)
None of these comments would give Gary Ferrington any peace while trying to get some rest in his appartment on the night of the U2 concert. The annoyance of the sounds penetrating his acoustic space far overshaddowed any possible hearing loss. The same must be said for all those who phoned the police to complain. And, based on the quotes above, it is possible that even for the audience at the concert hearing loss might not be a concern. (The sort of low frequency, even sub-sonic, high intensity thrashing that Ron Pellegrino mentioned is a completely different matter.)
We cannot condemn U2 merely for being loud. That´s part of the message, even the aesthetic, of their idiom. What we must condemn, I think, is the unwanted untrusion of sound into another's acoustic space. And it's not a matter of just insulating one´s self against this intrusion; but a matter of who´s in control.
Edwin A. Karlow, PhD........................909-785-2143 physics
Department of Physics...................................-2310 honors
Coordinator, Honors Program........................-2215 FAX
La Sierra University
Riverside, CA 92515
My first thought while reading Dr. Karlow´s posting on the literature and scientific studies of "loud music and hearing loss" was "For which hearing aid company does he work?" The examples quoted remind me of the studies in the 60s and 70s cited by scientific representatives of the tobacco industry to create a smoke screen around the connections between cancer and tobacco, the American Medical Association´s pronouncements in the 70s and 80s rejecting the value of food supplements and alternative and nonwestern medicine, and recent position papers on global warming and the reduction of the ozone layer taken by academic scientists working with grants from the automobile, energy, and chemical industries. Audio consciousness is a slowly rising wave and the World Forum of Acoustic Ecology is its leading edge. We can expect barriers and challenges from all established sources. People driven by habit, dogma, and vested interest are slow to change; but, with enough of the right kind of pressure, they will change and adapt if what´s offered can be shown to be in their best self-interest.
Some thoughts on specific items in the text of Dr. Karlow"s posting:
"We cannot condemn U2 merely for being loud. That´s part of the message, even the aesthetic, of their idiom. What we must condemn, I think, is the unwanted intrusion of sound into another's acoustic space. And it´s not a matter of just insulating one´s self against this intrusion; but a matter of who's in control."
RP - I think Dr. Karlow"s comment on "the unwanted intrusion of sound into another's acoustic space"hits the target. In fact, any unwanted sound, soft or loud, sweet or nasty, creates a multidimensional envelope that does more than intrude - it takes over not only your acoustic space, but your mind space as well. Acoustic intrusions reduce your freedom of thought. There is no escaping sound. It meets your body and forcibly enters your mind, not just through your ears but also via your bones, your flesh, and your body cavities.
An acoustic space can range from temple to torture chamber. As you move through the day you normally have little or no control over the acoustic space you share with your neighbors unless you´re willing to fight for that control and that means paying for it with your peace of mind. But at home you do expect to have control over your own space, including the acoustic space, and any intrusion is unwelcome and unbalancing.
"It does however seem that research has failed to lend substance to the belief that all those involved with rock music or discotheques will be deaf by the time they reach the age of 30..."
RP - Who is represented by "all those involved?" - The musicians? The audience? The audio engineers? The people who love to park themselves in front of the speaker stacks? And what does "deaf"mean? - Stone deaf? Hearing loss in the mid-high frequency range (2 - 5 kHz) which is common for audio engineers? A complete permanent threshold shift over the entire frequency range? And what about hearing loss at ages 35, 40, 45, 50, or beyond caused by overexposure at a young age?
"However, few patients attending the Royal National Throat Nose & Ear Hospital [in London] during this period have more than minimal permanent changes in their hearing sensitivity attributable to these noise sources, among an approximate 10,000 new cases of deafness seen each year."
RP - What are "minimal permanent changes?" - Just a few dB of loss here and there? And who are these "patients"? How old are they? Was the study based on asking them how they came by their deafness? The average person is as unconscious about their sound environment as they are about the quality of air they breathe, water they drink, food they eat, and garbage they leave in their wake. For example, most American males 55 years and older have more hearing loss in the left ears than in their right ears. If you asked them what caused that hearing loss, most of them couldn´t tell you it came from years of driving their unair-conditioned cars with the window rolled down. Were they stupid? Probably not. Were they unconscious about the damage being done to their left ears by the air jetting through their open window? Undoubtedly yes, but it certainly was a lot cooler than driving in a closed car in the heat. Drivers with the window down are sitting in the midst of a giant air reed. The faster you go, the more powerful the jet, and the greater the amplitude of the frequencies spanning the hearing range but especially intense in the high frequencies.
"In the context of pop music the resulting hearing loss is *less prevalent* than nodules on the larynx of vocal performers."
RP - This is one of those classical "handwaving" arguments meant to confuse and hypnotize the reader. What´s the connection between hearing loss and nodules on the larynx? Numbers of incidents? Toe nail fungus is less prevalent than acne. So what? Any music-caused hearing loss should signal an alarm. Music should be the celebration of hearing not the destruction of it.
"The weight of evidence suggests that music as a cause of noise induced hearing loss is nowhere near as damaging as what might be described as conventional industrial noise, or as prevalent as many would have us believe..."
RP - This is another strange comparison. Why should music be "damaging" at all? Why should sound of music be compared with sound of construction equipment, transportation equipment, or any other industrial noise source.
What follows is material that was not included in my email message posted on the World Forum of Acoustic Ecology but included here for people interested in matters closely related to that posting.
Emerging from my experience of working in technology and the arts since 1967 is the fundamental principle that test takers, study interpreters, equipment designers, and engineers are not to be completely trusted in matters that relate to perception and the arts. They all base their arguments on statistics. And as we all should know, statistics can be manipulated, twisted, and biased to prove any point from any perspective. Plus, one wrong premise or one excluded factor and their conclusions will do more harm than good or at best be worthless. What counts most in perception and the arts is the personal experience. I´m not saying that the work of statisticians and scientists is without value; what I am saying is that the ax they are grinding may not cut it with perception and the arts. The work of statisticians and scientists in the sphere of perception and the arts must be considered skeptically.
A good example is that most audio equipment designers and engineers continue to insist that since even the best human hearing tops out at around 20 kHz, there is no reason why audio equipment should respond above that 20 kHz. They must be forgetting about the physical phenomena of summation and difference tones produced by interacting fundamentals and partials, both harmonic and inharmonic. Frequencies above 20 kHz produce multiple orders of difference tones that fold over into the human hearing range and help to account for the greater richness of acoustic instruments over their recorded electronic representations. At one time or another in their educational program these scientists must have spent some time experimenting with two function generators putting out supersonic frequencies beating against each other to produce audible frequencies, an audio effect called heterodyning. All orders of difference tones generated by supersonic frequencies have important roles in giving life and color to the sounds we hear. Cut out the signals above 20 kHz and sonic vibrancy is diminished significantly.
When conducting studies, statisticians and scientists like to average. Music lovers, audiophiles, and people who care about acoustic ecology are by no means average. They represent a small portion of the human population´s top percentile in terms of audio sensitivity and audio concern. Academic scientific hearing loss studies designed to allay concern are probably of limited value to that group.
When it comes to protecting your own ears, who and what should you trust? Your own considered experience or the academic studies of scientists? No contest; personal experience should always take precedence over statistics and the academic interpretation of statistics. Take personal responsibility for the health of your hearing.
Unfortunately the notion of personal responsibility has been on vacation in western culture for some years thanks to general laziness and the legal profession´s considerable success in concocting victim legislation and convincing people to use their legal services to sue individuals and institutions that have done them wrong, despite those same people unconsciously putting themselves in harms way by abdicating personal responsibility for the way they live. I doubt it will be very long before a lot of people will be in court suing companies in consumer audio, concert production, movies, trucking, construction, jet skis, dirt bikes, etc. over the loss of their hearing. There certainly must be some scout lawyers on the lookout for new sources of revenue. Avoid the legal hassles by carefully picking your times and places for acoustic experiences and, just in case, save your hearing by carrying ear plugs to protect the jewels.
Common sense usually wins out over academic science. Look into an extremely intense light source such as the noonday sun or a laser and you´ll overdrive your retinal cells and lose your ability to see. A flash of bright light will temporarily blind you. Subject yourself to multiple closely spaced flashes and you run the risk of permanently impairing your sight. Why would anyone expect it to be any different for the ear? Park yourself behind a jet engine for awhile and you´ll likely go deaf or mad with the pain. Locate yourself in front of a speaker stack (some people do) at a rock or blues concert and you´ll definitely leave the show with temporary threshold shift (a significant loss of aural sensitivity) and probably a headache from an overabundance of neural firings. Repeat the speaker stack trick often enough and the threshold shift goes from being temporary to permanent, in other words, loss of hearing or deafness.
The eardrum can only stretch so far; it can be ruptured by loud percussive sounds. The ear also involves mechanical structures that, despite natural protective systems (such as the acoustic reflex which helps to protect the ear drum and the oval window of the inner ear from loud sounds), are easily overdriven by many of today´s power tools found in the home, yard, street, office, factory, school, and concert venues.
And what about the issues related to the effects of intense and insistent acoustic stimulus levels on the human nervous system and an individual´s sense of well-being? Living as we do in the death screams of the industrial age (all that talk about new age, technology, information, and communications notwithstanding) discussions of issues, acoustic or otherwise, that relate to the internal or spiritual life are mostly drowned out by the cultural din or simply given a deaf ear. And that´s a subject for another page, another time.
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