@MangoDragonFruit
This is a 2014 letter from OSHA to a representative of an employer. It clearly states that with the proper documentation, a hearing aid (of some type) may qualify as a noise reduction device to bring sound to acceptable levels. I am extensively quoting the relevant part below:
Background: You describe a situation where an employee with a congenital hearing loss works in an environment with noise levels measured between 85 and 93 decibels A-weighted (dBA). The employee in question utilizes a full insertion, programmable hearing aid that limits noise passing through the device at or below 85 dBA. You report that in the ten years employed, the individual has had no discernable standard threshold shift (STS).
Question: If the hearing aid manufacturer can produce documentation of a noise reduction rating (NRR) for a programmable hearing aid, would OSHA consider that device as an adequate hearing protector under 29 CFR 1910.95?
Response: Yes, an assigned NRR is a manufacturer’s rating of the device’s effectiveness to attenuate noise. As you are likely aware, the adequacy of hearing protection is determined by the effectiveness in attenuating or reducing noise that reaches the inner ear. This measure of effectiveness is called the NRR. The NRR is a laboratory-derived numerical estimate of attenuation that is provided by the hearing protector. The U.S. Environmental Protection Agency (EPA) requires manufacturers of hearing protection devices to identify the noise reduction capability of all hearing protectors sold in the United States, and to present the NRR on the package label of the device1 . We are aware that some manufacturers of hearing aids have also designed hearing protection into their devices with an assigned NRR.
To evaluate the adequacy of any hearing protector’s attenuation, the employer must refer to the mandatory Appendix B to 29 CFR 1910.95, as required in paragraph 1910.95(j)(1). The NRR of the hearing protector is compared to an individual worker’s noise environment to determine whether the exposure is attenuated to the level required by the OSHA standard. For employees with no STS, the hearing protector must attenuate noise exposure to an 8-hour time-weighted average of at least 90 dBA, as required in paragraph 1910.95(j)(2). For employees who have experienced an STS, the hearing protector must attenuate exposure to 85 dBA or below, as per paragraph 1910.95(j)(3).
Source: Occupational Noise Exposure - The use of hearing aids as hearing protection devices. | Occupational Safety and Health Administration (osha.gov)
So I would think that such hearing aids must be very occlusive hearing aids, perhaps custom-in-the-canal (CIC) with no vent, etc., no metal receiver body running the length of a mold to conduct sound, etc.
There is something strange about your sound situation. Since you cited “27% reduction” required, I thought, “Geez! Must be at 110 dB having to get down to 85 dB allowed for 8-hour exposure!” But you’re already at ~85 dB but work a 12-hour shift. The way these things work (my ignorance showing here), is there is a trade-off between time and loudness allowed. For OSHA in industrial settings, I believe the loudness step is 3 dBA. If the noise level increases 3 dBA above 85 dB exposure, you have to halve the exposure time.*** If you decrease the exposure 3 dBA below 85 dB to 82 dB, you can double the exposure time - you could work 16 hours a day at 82 dB exposure, in my limited understanding. Things get more complicated if the noise is not ~constant all day long. If some part of a shift, the noise shoots way up, that’s going to cut way down on the time allowed. You have to use a time-weighted average but I’ll skip the details for now.
Basically, the above means if you are pretty much at 85 dB your whole shift, you only need a very modest amount of noise reduction to get down to 82 dB or so. You shouldn’t need 30 or 40 dB of protection (although it might be better for preserving your remaining hearing long term).
As far as comfort of ear muffs or headphones, have you looked into headphone wraps? These are cushions that go on the headband connecting the two ear cups and lessen the pressure of the headband on your skull. I am not recommending Microsoft Surface Headphones but I have a pair of those and they are very comfortable to wear for hours-the cup material is very squishy (silicone in-fill??) and the cups fit snug but deform to reduce pressure-the headband is adjustable, too. So perhaps finding a comfortable ear muff or headphone is just a matter of finding one that is as adjustable as possible, doesn’t CLAMP your head, and wearing a headband wrap also, if needed.
But if the OSHA opinion in the letter that I cited still stands, perhaps your problem can be solved just by getting or documenting the appropriate NRR for your HA. I would think with the type of calibrated microphone used in REM, that an audiologist could actually document the noise level that is reaching your ear drum in a suitable test set-up if OSHA would let your employers know exactly what needs to be documented.
Hope some of my blather helps. Hope others like Raudrive will continue to chip in with their expert advice. Maybe your audiologist or hearing care provider should contact Phonak or the manufacturer of whatever new hearing aid you might want to get to see if the particular model you’ve chosen has been tested for a NRR (Noise Reduction Rating). Perhaps if a HA with a suitable work NRR is not what you really like, you could have two HA’s - one for work that you grudgingly wear, one for the rest of the time that you enjoy wearing more that doesn’t have a NRR.
*** The reason for doubling or halving allowed exposure time in only 3 dBA steps down or up is that dBA steps are exponential steps, not linear, directly proportional steps. Something more complicated than simple arithmetic is involved.
