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Re: [AUDITORY] How to speak to people about hearing loss and high sound pressure levels

Dear Kevin,

This is indeed a very good question.

I don't know the legislation where you are, but most European countries have one for sound levels in public environments. However, most of the time it is completely unrelated to the limits imposed on workplaces, and has actually little to do with health and safety at all. For instance, in France, the level is limited to 105 dB-A (Leq for 15 min, 120 dB-SPL peak). No doubt that there's enough in this to induce hearing loss.

The crazy thing in all this is that these loud public event generally don't run themselves by themselves, and the public is generally not left on its own. There is a lot of staff, and while some of them can wear ear plugs, a fair number of them can't because they must hear orders from customers, or because they have the hand on the volume knob and are supposed to check what's going on sound-wise...

I used to teach to these guys, sound technicians/engineers, a short introduction to hearing. What I remember is that there's a lot of myth and legend in the field: they know next to nothing about how to preserve their ear even though this is their primary professional tool (deaf sound engineers don't have the best reputation). Backstage, they hear things like "ears are like a muscle, you need to train them: the louder the sound, the stronger your ears become". Actually once you've killed that myth (by playing simulations of hearing loss, cochlear-implant, tinnitus, hyperacusis...), they get pretty concerned. And with the concern for their own health, you may expect that they would be more concerned about the public's health.

Now, only when this knowledge is ubiquitous in the profession will the tech guys have the guts to tell the producer/employer that they shouldn't do it. In the meantime the only thing that can bend these people, is the prospect of getting brought to court for rendering someone deaf.

And actually it already happened. I only know of examples in France, but it must have happened in America too. In France they talk about a concert of Ben Harper in Grenoble (29 March 2000) where 6 people in the audience ended up in hospital for ear damage, and one of them attacked the organizers in court (I added a bit more details about in the PS). I haven't been able to check more, but the legend says he won, and the whole benefice from the concert went in the payment of compensations for that person. Since, concerts are apparently limited at 95 dB-A in Grenoble. People don't seem to have noticed, but nobody was sent again to the hospital. Another example: U2, Marseille July 1993, same story. I'm sure there's enough material to scare the organizers out of doing the stupid thing.

So I think the right discourse is to stress that keeping levels low is not about making the old neighbours less cranky, it's not about being nice... it's about health and safety, about preserving your professional tools (be they employee or your own ears) and about running your business in a sustainable way. The last straw is that the only argument against turning down the level is that "people won't enjoy is as much". But while there's actually no proof of that at all, there quite a large literature on NIHL... (more on that in the PPS)


PS: More about the case in Grenoble. Again this is what I've heard from sound engineers. These big concerts use directional systems (line array, or phased array, or "system V-DOSC"). The common problem that sound engineers face is that there's a large crowd, and sound needs to travel and gets attenuated while doing so. With a directional system, you can try to have a more homogenous sound level in the audience: you jack up the higher beams to reach afar, but keep the lower beams relatively softer to avoid deafening (instantly) the audience close to the stage. Nice on paper, but if you mistune the system (which may apparently have been the case in Grenoble), you may do worse than good. And even worse, if you don't have that system but are used to it, you may forget that you should not have 95 dB at the console at the back of the audience...

PPS: Regarding how enjoyable loud music is, I think there is quite a large source of evidence that loudness can be subjective and context dependent. Actually this is a trick that experienced sound engineers sometime use: when a musician thinks is not loud enough, for instance, the right thing to do is to lower his level, then when he/she's unhappy, put it back to where it was... that generally makes one happy musician...

Etienne Gaudrain, PhD
UMCG, Afdeling KNO
PO Box 30.001
9700 RB Groningen

Room P3.236
Phone +31 5036 13290
Skype egaudrain

Note: emails to this address are limited to 10 MB. To send larger attachments, please use egaudrain.cam@xxxxxxxxx.

On 13 October 2013 07:09, Kevin Austin <kevin.austin@xxxxxxxxxxxx> wrote:
An on-going topic -- very high level [dB] sounds, hearing loss, personal and societal responsibility.

Once or twice a year I am invited and go to an event where the sustained sound pressure [dB] levels will be in excess of 95dB, and often into the 105 - 110+ dB range. I am usually long gone before the levels have drifted up to this point, however they usually start in the 85-90dB range. I use a combination of Vaseline [petroleum jelly], and water- [spit-] soaked paper tissues / Kleenex, to seal my ear canals. At the last two events I left, about 20% of the people were babies or children under 7-9. They were brought close to the speaker stacks, and the younger children enjoyed playing in front of the speakers.

My question is not one about NIHL etc, which is documented, but rather one of how to speak to the people responsible, before and/or after the event about the damage that is being caused by these environments. If this were a work place, there would be laws, rules, regulations and ways of changing the behavior. In these social environments, rules and regulations don't apply. And I'm talking 3 or more hours of continuous 105+dB.

There are currently two students in our university electroacoustic studies program who have reported their hearing condition to me in some detail, along with audiograms, and possible hyperacusis. Discussing this with many younger people tends towards the "teenage invincibility syndrome" [will never happen to me], and in older people, there is a general ignorance or lack of understanding, often paired with an attitude that indicates, "if it really is a problem, there would be laws about it". There are. But, in my experience, there is a fundamental ignorance of what happens, and what has been happening for the past 35 - 40 years.

As the professionals in the field, what can be done? and how can it be done? Is it a matter of this "silent plague", simply eating up the hearing of those who are under 40 such that they will not be able to hear in 15 - 25 years.

Recently, this appeared:

Thu, 09/12/2013
>> Blake Wilson, Graeme Clark, and Ingeborg Hochmair were awarded the Lasker Award this week for their contributions to the development of the cochlear implant. The Lasker Award is essentially the American Nobel prize, and  this is an incredible recognition of not only the importance of cochlear implant technology but also a much broader acknowledgment of the importance of hearing and communication by the entire scientific community. There will be several events over the next few months building on this recognition with interviews with the Lasker awardees, a dedicated one-hour show on PBS with Charlie Rose and Eric Kandel on hearing, and finally a two-day workshop sponsored by the Institute of Medicine on hearing loss in older adults in January.

It is noted that this seems to be mostly about cochlea-based hearing loss in older adults.

Other items on stem cell research growing back hair cells have been seen in the media. However, these reports do not address a major cause of the problem, exposure to high dB levels. As I understand it, this developing technology may have little effect on tinnitus caused by nerve damage.

Are there ways to have the media take cognizance of and report on the dangerous environments which persist?

As professionals, is there any individual or group responsibility regarding making this better known and the [likely] consequences more clearly understood? Is this like the cigarette situation where the 'evil' is not only socially acceptable, but expected so that the event has 'street cred'? Club owners and Rave organizers want blood-letting levels, "because the customers want it".