Types of hearing loss, and the complaints that arise

[Solstace]

So I work for a church, and we are attended by a wide variety of people. Many seem happy enough with how (much) we amplify speech and music, but there are some who find our amplified music too loud. Now, as someone of reasonably able hearing I would suggest the levels are reasonable (60-70ish dB speech, peaking 90-95dB music) and that despite significant challenges the overall balance and 'EQ' of our mixes tends to be pretty good. On the other hand, having suffered hearing loss in the past (and on speaking regularly with some who still do) I can understand that (ironically) louder music can cause significant issues of pain and/or discomfort, whether hearing aids are used or not.

 

What I'm wondering is...

 

...does anyone here have an understanding they can share with us on what kinds of hearing issues are out there, and how the effects of these can be explained/demonstrated to those of us with more normal hearing?

 

To start us off, I understand that there's the most basic kind of loss, and that this typically involves a mixture of straight attenuation either across the whole frequency range, or affecting specific frequency ranges depending on the cause of the loss. This information is commonly available on the RNID site among others.

 

On the other hand, I have some people complaining of louder sounds causing an audible artefact of sorts - somewhere between distortion (just like clipping in an amplifier circuit) and modulation. I experience something like this myself - if something isn't EQ'd right, I often hear it as a buzzing/beating sound over what I perceive should be the original signal. I even learned to EQ by it, and it has become for me an intuitive and (on peer evidence gathered over 10+ years) surprisingly accurate method, regardless of the calibre or condition of the sound system I'm using or the source material feeding it. Is there a name for this kind of effect and/or condition, and does anyone know of any causes? Further, does anyone know of any coping mechanisms (physical or psychological) that can help 'punters' deal with this kind of issue, or that might help us in preventing/lessening the issue when we're not aware of it ourselves?

[mervaka]

I think for me, my hearing loss and my tinnitus are probably linked. my hearing loss is mainly between 6-12k, and just sounds like you'd expect a cut to sound like. my tinnitus sounds like a ringing, with a fundamental at around 6k.

[ramdram]

Solstace, the theatre where I volunteer put all their staff, not just FOH, on a course for just the issues you are asking about. I gather there are organisations who visit places of work to give lectures on disability.

 

This theatre arranged for other speakers to give lectures on various other disabilities too, such as folk in wheelchairs...not so much about them physically getting around but how to deal with any issues they have as tactfully as possible. Needless to say really, but being patronising is about the most heinous crime you can commit. All this training came under their "Customer Care" program.

 

One thing that did take me by surprise, sort of, and it shouldn't, is that age is no bar to being disabled, in any way. One exhibition we went to in Plymouth brought this home to me in that I saw two drop dead gorgeous young women reading some of the blurb on a stand, then they turned to each other and started signing.

 

By far the majority of folk to whom I hand out the headphones (connected by IR to the stage relay) are elderly (my age, ** laughs out loud **) and they are experiencing age related hearing loss to a certain degree.

 

Suggest you do the google thing. To start you off you might try here (and as always, apologies if you knew this already):

 

http://www.rnid.org.uk/?gclid=CKfZ05H4rqQCFctA4wodEzKTzw

 

If anybody knows about hearing probs in relation to everyday life then they do.

 

HTH

[Solstace]

Yup - the RNID site is indeed really helpful towards the understanding of straightforward hearing loss and its causes - tick.

 

What's left is finding out about the more 'subtle' issues, such as some people finding any music at anything louder than 65dB physically painful, complaining of having their ears "distort" at what most of us would consider relatively low SPL's, etc. Anecdotally I suggest that in our church we get more complaints by far about these more subtle issues than about any other. Okay, it might be three or four people per week out of 2-3000 coming through our doors, but surely even *that* many people can't just be making it up? And on talking with them I wouldn't say that they are having any trouble following our conversation, even during the soundchecks or rehearsals that they're complaining about.

 

I'm thinking something's up here that I'd like to have a better understanding of, but nobody I've yet met who has had such complaints knows enough about sound or hearing terms to understand what they are actually hearing, let alone explain it to a technician. The language and thinking structure doesn't exist, and patience wears thin very quickly despite the best of efforts.

 

Frankly, Uncle Google isn't much help here. Most resources it finds are simply subtly different (Americanised) versions of the (admittedly excellent) RNID advice. So I thought: "Who better to ask about this stuff than a bunch of other pro's who might well be facing the same kind of questions?"

[Shez]

What's left is finding out about the more 'subtle' issues, such as some people finding any music at anything louder than 65dB physically painful

Have a google of Hyperacusis for that one.

[Simon Lewis]

I knew my hand written acoustics notes would come in handy one day...

 

–Loudness Recruitment:

here the sufferer can hear “quiet” sounds (i.e. loud enough to hear!), but as the level is increased, it suddenly appears as uncomfortably loud to the listener. This is the term applied to those who have sensorineural hearing loss. In those with ‘normal’ hearing it is called hyperacusis.

 

You may find more useful searches via Google Scholar, but this often goes too far the other way and you need a medical degree to make sense of it. Occupational Audiometry by Maryanne Maltby is quite a good read for general protection of hearing at work, but doesn't quite deal with the concert end of things.

 

The issue is that these people are experiencing a very real problem with louder sounds, and whether by level adjustment, location, spectral balance, ppe or PR we do need to manage their needs.

 

Simon

[ramdram]

Granted you may have to dig but using the helplines set up by the RNID might be worth considering.

 

What folk may find tho' is that not having a medical background renders a lot of the gen just "jargon". EG, the Hyperacusis info opens up so many links that you would never be able to read them all, let alone actually understanding the medical terms.

 

Perhaps it might be of more use to investigate known technical solutions to hyperacusis and work from there? Which might mean going back to the RNID.

 

Ref your thoughts about asking pros for their thoughts...this is the first thread I have read on the subject of hyperacusis so you may be the first to raise the issue anyway.

[matt_beal]

Hi BR,

 

As a medical student I thought I might have a go at summarising some of what I can find for you. I haven't studied neurology yet, but I should be able to make sense of the jargon and do some translating!

 

The first thing to understand is that Hyperacusis is a symptom, as opposed to a disease in itself.

 

Hyperacusis doesn't appear in any of my general clinical textbooks, and I don't have time to do a proper literature search, but Google Scholar has just come up with an article which I think summarises it all quite nicely. If anyone can find a better source let me know and I'll happily summarise.

 

Definition: Hyperacusis is a consistently exaggerated, or inappropriate neurological response to sounds that are non-threatening, nor uncomfortably loud to a typical person.

 

Who gets it: There is a massive lack of robust evidence. The studies reviewed suggest that between 8% and 15% of all people complain of Hyperacusis.

 

Of people complaining of Tinnitus, 40% complain of Hyperacusis. Of people whose main complaint is Hyperacusis, 86% have Tinnitus. This suggests that the conditions may be related in some way.

 

Causal Factors: In the majority of cases, no cause is identified. The common conditions that Hyperacusis has been reported as a symptom include: Migraine, Depression, Post-Traumatic Stress Disorder (PTSD), Head injury, Lyme's Disease (infection caused by Tic bites), Williams syndrome (genetic neuro-development disorder)... amongst some other conditions.

 

Mechanism: Hyperacusis has several suggested mechanisms, although none are proven. The first is a problem with Serotonin causing sound signals to be interpreted wrongly. Serotonin is a neurotransmitter (chemical signaller) that is responsible for transmitting signals from nerve to nerve, and from nerve to effector cells. Other conditions where Serotonin is disturbed include Migraine, Depression and PTSD. The other suggestion is that there may be some over excitation (i.e. too much activity) within the area of the brain where hearing is controlled and interpreted.

 

 

Therapy: There is evidence that ear protection does not work as it increases "internal gain" making the condition worse. Tinnitus Retraining Therapy (TRT) has been suggested, although there has been no real proof that it works. TRT works by desensitising the ears, or at least the interpretation of sound. Cognitive Behavioural Therapy (CBT) has been suggested as the treatment of choice, although it deals with the psychological stress caused by Hyperacusis, rather than dealing with the actual symptom.

 

I hope this rather (very) rushed summary answers some of the medical questions... if not feel free to send me something else to translate!

 

If you have any specific questions let me know and I'll see what I can dig up in the library.

 

Matt

[ianl]

I find that in a noisy room ie lots of people and hard surfaces (ie a pub club or church) I strugle to hear the thing I want to hear (be it PA or some one talking to me) over the uniteligable and confusing "noise " of lots of people talking or moving about

 

in this situation the threshold between being able to hear the thing I want to hear and pain is a very small amount. to the extent that someone will say something that I can't hear so they repeat it louder and I just get pain and distortion.

 

I get the same thing with PA systems if theyre not just right for me, went to see bon jovi a couple of years ago and it was too loud for me, I really couldn't tell what song they were singing, it was only when they played a balad that I could tell what it was and enjoy it

[swampman]

Church related problems - from experience...

1. Can't hear sermon, vocal lead or melody line : usually occurs when hubub level is less than 30dB (!) from what they should hear (rule of big thumb) so persons cannot seperate relevant sound from noise.

2. Lack of clarity; enhancement of more information loaded sounds: t, s, v, p... [consonants] the 2-6kHz region; but too much and it becomes painful and usually identifies a pair of dud ears on the desk .....

 

The TOO LOUD ones:

3. "May I suggest that you sit further back" - cannot always be said it to visiting preacher's wife placed courteously on front row in front of the PA on stands(!)

 

4. Long term: move main speakers to a more balanced placement (near the rostra) so that the dB decay with distance is more spread to the receiving ears: usually needs hanging high up and probably behind 1st row (they would be able to hear speaker or monitors)...

 

5. Have a high level area for the ones who like it loud and make that visible (For some Spanish Pentecostals that may mean the whole church at 95dB or minimum 4kW PA + monitors !!)

 

6 Distribute your dBs: that is place speakers around the auditorium with delays as needed: this balances overall level and stops the peak areas at the front.

Easy excercsise: draw your auditorium/church to scale: using a compass from the placement of your speakers mark the 1m, 2m, 4m, 8m radius.... this will give you an idea of the dB reductions of direct sound travel - you can then work out the quieter areas. Or get a computer progamme to do it for you. Try out different placements and powers.

 

7. Use a system limiter/compressor to cut excesses/accidents - though a compressed sound becomes hammering and lacks contrast/depth.

 

8. Have a dB meter to hand to show - they cannot argue with science and an established level!

 

Note: one important social aspect is that for many the church they attend is the noisiest thing that some people go to voluntarily. Street noise, the washing machine, the TV etc are things they can control or avoid... but at church their expectations for personal comfort remain high and often lack sympathy for other more lively members.

Very interesting the medical explanations above: may I add that many who live "a quiet" life may become excessively sensitive since the ear muscles are not excercised regularly to "clamp the ear drum", nor may their brains' audio filters work adequately: e.g. how do we distinguish relevant speech/noises in a noisy place like a street, station or airport...?

[Solstace]

Wow - some really interesting thoughts appearing here. At least now I've got some more info to arm my Google hunting.

 

To reply to Swampman's thoughts and hopefully give a better idea of where *I'm* at...

 

Re 1) We're aiming for speech to be nominally 20dB above background throughout the building. 30 is better but everyone feels like they're being shouted at when we go there. So we don't. Which is good because 20 is often a struggle against whispering readers and feedback.

 

Re 2) Clarity tends not to be too much of a problem, except that so much of the damn stuff is reflecting around the building. Especially when it's very humid, I notice.

 

Re 3) People tend to sit where they have to, either through function (read "preacher's wife" situation mentioned) or depending what time London transport allows them to get into the building. A few might get there super-early, then complain about rehearsals being too loud when they don't even *need* to be in the building, but otherwise have nowhere else to go for whatever reason. This latter category might tend to sit in the same place week in week out for 20+ years - change isn't something suggested or taken lightly.

 

Re 4) Decay is actually pretty good when measured, with our system. Reflected and ambient sound are bigger issues. Especially when louder acoustic instruments (think drums, orchestras) are present.

 

Re 5) Not really possible in our building. Loud in one spot will mean louder but with less mid/high clarity (and more audible reverberation) in another.

 

Re 6) Done as closely as funds, existing technology and faculty/planning/listing permissions go. Intention is to look at this in the coming year or two as funds (and need) allow.

 

Re 7) Dynamics processing helps a little, but is no substitute for a well-trained and switched-on human operator.

 

Re 8) Numbers mean nothing when physical pain is a symptom. Showing someone that it's less than 90dB is all well and good, but doesn't help either party when the complainant is telling you you're hurting them. Neither does showing them the nominal 3-6dB drop in music levels when the PA is turned off. It's still too loud to them, and that's all that matters.

 

Church related problems - from experience...

1. Can't hear sermon, vocal lead or melody line : usually occurs when hubub level is less than 30dB (!) from what they should hear (rule of big thumb) so persons cannot seperate relevant sound from noise.

2. Lack of clarity; enhancement of more information loaded sounds: t, s, v, p... [consonants] the 2-6kHz region; but too much and it becomes painful and usually identifies a pair of dud ears on the desk .....

 

The TOO LOUD ones:

3. "May I suggest that you sit further back" - cannot always be said it to visiting preacher's wife placed courteously on front row in front of the PA on stands(!)

 

4. Long term: move main speakers to a more balanced placement (near the rostra) so that the dB decay with distance is more spread to the receiving ears: usually needs hanging high up and probably behind 1st row (they would be able to hear speaker or monitors)...

 

5. Have a high level area for the ones who like it loud and make that visible (For some Spanish Pentecostals that may mean the whole church at 95dB or minimum 4kW PA + monitors !!)

 

6 Distribute your dBs: that is place speakers around the auditorium with delays as needed: this balances overall level and stops the peak areas at the front.

Easy excercsise: draw your auditorium/church to scale: using a compass from the placement of your speakers mark the 1m, 2m, 4m, 8m radius.... this will give you an idea of the dB reductions of direct sound travel - you can then work out the quieter areas. Or get a computer progamme to do it for you. Try out different placements and powers.

 

7. Use a system limiter/compressor to cut excesses/accidents - though a compressed sound becomes hammering and lacks contrast/depth.

 

8. Have a dB meter to hand to show - they cannot argue with science and an established level!

 

Note: one important social aspect is that for many the church they attend is the noisiest thing that some people go to voluntarily. Street noise, the washing machine, the TV etc are things they can control or avoid... but at church their expectations for personal comfort remain high and often lack sympathy for other more lively members.

Very interesting the medical explanations above: may I add that many who live "a quiet" life may become excessively sensitive since the ear muscles are not excercised regularly to "clamp the ear drum", nor may their brains' audio filters work adequately: e.g. how do we distinguish relevant speech/noises in a noisy place like a street, station or airport...?

[Sam Jelfs]

I find that in a noisy room ie lots of people and hard surfaces (ie a pub club or church) I strugle to hear the thing I want to hear (be it PA or some one talking to me) over the uniteligable and confusing "noise " of lots of people talking or moving about

 

in this situation the threshold between being able to hear the thing I want to hear and pain is a very small amount. to the extent that someone will say something that I can't hear so they repeat it louder and I just get pain and distortion.

 

I get the same thing with PA systems if theyre not just right for me, went to see bon jovi a couple of years ago and it was too loud for me, I really couldn't tell what song they were singing, it was only when they played a balad that I could tell what it was and enjoy it

 

 

Ahh, so this would be my area then :D The general thing you are talking about is the "cocktail party problem" ¹, and a lot of it is based on the location of the sources, rather than their actual levels, main points being dont have the target person in front of you, but have them off to one side, pref with the loudest interfering noise on your other. Then there is two mechanisms at work helping you, better-ear listening (ie, which one has the better SNR), and binaural unmasking, which is a higher level processing that makes use of ILDs and ITDs to "cancel" the interferer^2,3

 

On a more general note, I would suggest looking at level of the stuff coming out of the PA, with respect to frequency. Dont forget that the critical speech band starts to tail off quite quickly after 3-4kHz, the ANSI SII standard only really takes into account the freq up to 4kHz. At a guess the stuff that is "painful" for people is much higher in freq than that... When you say its 90dB, look at the weighting used, it might be 90db on the meter, but the HF might be a lot higher than that. Pref measure it with something like Smaart and see if you can run a lot of the HF off without compromising the sound too much, it may help... Also, see if one of the people that has these issues is available to come along at some point other than a service, and help you diagnose the problem, put some play back material on, start messing with levels and EQ and see what it is that affects them, they are after all the best people to advise on this.

 

 

 

1 - Cherry, E. (1953), ‘Some experiments on the recognition of speech, with one and with two ears’, The Journal of the Acoustical Society of America 25(5), 975–979.

 

2 - Durlach, N. (1963), ‘Equalization and cancellation theory of binaural masking-level differences’, The Journal of the Acoustical Society of America 35(8), 1206–1218.

 

3 - Durlach, N. (1972), Binaural signal detection: Equalization and cancellation theory, in J. Tobias, ed., ‘Foundations of Modern Auditory Theory’, Vol. 2, Academic, New York, pp. 371–462.