Thank you tedtan for that article.
Since it was published the Health and Safety Executives both in Europe and America have revised their recommendations downward.
As more evidence of the damage to hearing by sustained noise levels has become apparent and regulatory authorities and employers have become more risk averse in the face of litigation from unions for affected employees.
You make a good point regarding the size of listening room and the 85 dB level (now today reduced further) for cinema sized mixing rooms such as those found in Hollywood or Pinewood or the major recording studios that they utilise.
Your excellent point reminded me of a church meeting I visited some time ago where the morning service was in a huge hall with a suspended array P.A. system. However, they had an evening service in a much smaller hall, without a P.A. and the singers belted their voices out at full pelt. It was sharply painful and hurt my ears to be in the same room with them singing, and I was sat right at the back of the hall.
I was able to have an opportunity to speak with them at length afterward about the need to modify the dynamic of their vocal projection according to the size of the room. But really the problem was far less about their voices, and much more about the physical dimensions of the room they were singing in. Failing to understand that and make adjustment for the difference in size of venue. They were kind enough to drive me home afterward! 😊
Many people appear to think that sudden loud bursts of noise or peak levels of music are responsible for most of the damage done to hearing.
In point of fact, our ears do not respond quite in the manner most people imagine. They are predisposed to be adversely affected not so much to sudden transients or peak levels of sound, but rather to average or RMS levels of sound that are usually far lower, but also usually far more constant.
Therefore, the best way to think about this issue is not that your ears will be damaged by a sudden loud sound that takes you by surprise, but by constant, continual lower levels of sound, that your hearing is exposed to over a far longer period of time. It is the sustained period of exposure your ears endure that actually does the damage.
Time is the danger element. Long periods at an average lower level are more dangerous than short periods at a higher level.
Of course, if you set your monitoring level at a high level to start with. Quite apart from the peaks you might encounter, the average level you will be exposed to over a long recording or mixing session is going to be that much more potentially damaging to your hearing.
Your outer and inner ear features Sterocilla, groups of hairs that move when sound enters our ear canal.
These in the inner ear do not move in free air but are pushed about by an inner ear gel which moves them as a result of the various mechanism of the ear responding to sound.
We could liken these hairs to a field of wheat. You walk through the field once which doesn’t take long, and it appears no damage is done at all. The wheat moved around a bit but soon recovered.
But if you walk back and forth all for many hours, day long across that same field. Eventually you will notice that quite a bit of wheat has actually been trampled down. The stems have broken and they will never recover.
The hairs of the inner ear are grouped by frequency. So, what happens if you subject your hearing to long periods of sound without proper care, is that you may not really notice any actual loss of hearing at all at first, but you may have partially lost hearing at certain frequencies, dependant upon what you were listen to so loud for so long.
It is therefore often a gradual process of hearing loss, affecting different areas of frequency bit by bit. And by the time in everyday living under certain situations that you really start to notice your hearing just isn’t as good as it once was, lamentably, irreparable damage, has already occurred.
As tedtans article amply demonstrates, once you delve deeply into the matter of level setting, and it varies according to the situation, it can become a mind bogglingly complex business to get your head around.
Old pal Bob Katz who was here a while back lecturing, devised his K-System that some might find helpful. But for those easily bewildered by technical complexities I heartily commend the advice given earlier, which is so easy and simple to implement and follow.
Adjust your monitoring level so that for the overwhelming majority of the time, you could converse across the mixing desk with an engineer, hearing and being heard, without either of you needing to particularly raise your voice. This will be safe and the mixes you create at this level, will hold together well, regardless of what volume the end users set their Hi-Fi to.
Ace mastering engineer Bob Ludwig would at times have a client attending a session who wanted to listen to their mastered recording as a higher level than he normally utilises.
He would set the volume higher as requested without playing anything back, show the client the play and the stop switch. Then leave the room and the client to listen... without him. A professional approach.
Its that serious!