I had this discussion on the HLAA forum and got no satisfactory answer. The HLAA forum is pretty dead and on it's way out so I didn't get but one or two responses and they weren't conclusive. Also it is my fault because I don't think I explained myself clearly.
Please understand, I'm not trolling, I really want to know. If my logic is sound, I will only wear my aids when I need to instead of all day. I can't get along without them.
Let me divulge my logic (or lack of it):
1) I know that the sound level of 85dba ("A" weighted, slow response) for 8 hours per day permanently damages hearing. The DB scale is logarithmic function, each 3db is double the power of the one before. So at 91dbdba 2 hours of exposure damages permanently, at 100dba it's only 15 minutes, at 110dba it's mere seconds and at 120dba it's instant permanent damage. Logarithms are comparative ratios, adding the a suffix (dba) is referencing it against a standard, and is what all hearing tests use — db is a ratio and dba is a definite value.
2) Hearing aids amplify the frequencies you cannot hear as a reverse curve to your hearing loss audiogram
3) Say you have a 70 db loss in hearing at 3Khz (3,000 cycles per second), that means at 71 dba in a quiet hearing booth you can barely hear the faintest whisper of a 3khz tone. And like many of us, say your lower frequency hearing is either zero or around 6 dba. (note: most consonants are in the 2-4 khz range so this is where we understand speech)
4) Now say you are in a room that conversation level is around 75 dba, you will need about 75 db of the consonants to understand what the person across the table is saying to you. (Note: I have several sound level meters and 75db in a restaurant is average for one without loud background music.)
5) Since your hearing loss is at -70db, there is already 75dba of conversation in the room how high does your hearing aid have to amplify the 3khz sounds?
6) Do you have to take the 70db loss, add it to the 75dba conversation level in the room and amplify to an ear damaging 145dba? Remember, adding 70dba is your tiniest, softest, perception at the frequency in a quiet soundproof booth. So it seems 70dba wouldn't be enough. Hearing a whisper of a consonant in a 75dba room seems to me to be worthless.
So it seems to me that amplifying the ambient noise of the room above 85dba could slowly erode your hearing so you will need stronger and stronger hearing aids, which amply more and damage more, which means you will need stronger and stronger hearing aids, damaging more and more. etc. (feedback loop)
Or am I missing something?
If my thinking is faulty, please explain in detail and tell me why my logic is not logical.