Seems very similar to my experience from the words you describe although I would consider my left ear my āgoodā one simply because the losses I have there are in a less significant band. If you click on my audiogram under my username you can see a little of what I am describing. If you look at the audiograms of many other people, especially those with age or chronic-exposure hearing loss, usually you will see a relatively broadband loss thatās either relatively even across the audible spectrum, or more of a gentle sloping loss with bias towards the higher frequencies, as they are most vulnerable to loss. This is because they are concentrated at the apex of the cochlea, being the most vulnerable due to being exposed to the most sound, while also simultaneously having less concentration of hair cells responsible for those frequencies. This is more or less an inevitable thing and product of life like cancer- the longer you live the less of these cells you will likely have and the worse your hearing will be, just like how if you live long enough some cells in your body will simply mutate to a point where your immune system cannot deal with it and they will proliferate in the body. I think this is the ābestā situation one can be in terms of hearing loss, because it is more of a gradual loss of function that can usually be remedied quite well through simple broadband amplification, all the āmechanismsā of hearing are still there are more or less working relatively well as a unit, and there is more or less equal or at least progressive deficiency across the board, so it is more predictable to fix and yields better results. The hearing loss I have is the antithesis to this more or less- my hearing prior to the loss was extremely good, and even now I hear very high and very low frequencies completely fine. Great in fact. But important low/mid bands are completely scooped and carved out randomly, which makes mine an atypical case.
When I first found out about my hearing loss, it was tough. Through a battery of tests, MRIs etc I never got closure on how it happened and they found ānothing wrongā, and I have no idea whether is was really due to some acute noise exposure, some medications I was on, a vascular or immune problem or something of that nature. Seeing as how Iām young and can still manage conversations at regular volume (around 50-60 dB) with minor issue, but as a great music lover having it so impacted I figured āhey I will just use my audiogram as a template for applying parametric eq to my music in each ear so I can hear what I am actually missingā, but soon realised it is much more complicated than that. Luckily (or not), I have a very broad scientific knowledge and love for music and music reproduction, and while I am not an audiologist or ENT, Iām also a graduate of medicine and have been involved with medical research, I have a strong background in biochemistry and engineering, so I quickly found out a lot about my loss through not only my experience of dealing with this loss/running informal experiments on my function, but also through reading numerous books and medical papers on the subject. What I was never told by my ENT or my audiologist is that, based on the massive sudden drop of notches I have in each ear, these are actually likely very ādeadā cochlear regions where essentially, the cochlear function in terms of the signal transduction process is essentially wiped out due to one or more mechanisms, which I wonāt describe for the sake of making the post too long.
One thing that is misleading or not intuitive is that- if my audiogram is showing my thresholds are ~50 dB down at 500hz, Iām still hearing something, right? So why canāt that be amplified or corrected like Iāve seen done successfully in elderly populations? Well it seems most people, and I think even many hearing professionals and doctors in the field donāt understand (at least conceptually) is that, in a case where thresholds like this are past a certain point (especially if the rest of the hearing is relatively OK and there are sudden or random drops), the āthresholdā I am hearing at 500hz is not a 500hz tone at all, but rather is more accurately a āfalse positiveā noisy tone. The noise I am hearing at -50dB is NOT what any respectable musician would consider a pure continuous tone but it is a result of other non-dead regions of the cochlea (and maybe even the other ear) being stimulated at low levels giving the impression there is something being heard. A simple audiogram obviously does not reflect this, and no audiologist or hearing care professional has ever asked me if the pure or modulating tones I am hearing in an audiogram seem odd, different, ringing, sharp/flat etc. Speech in noise/word intelligibility tests can give clues, but it can easily be missed or overlooked. So for example in my case, my loss that is shown to be peaking at around 500hz should technically be virtually down to the bottom of the audiogram, that is something that can never be amplified for me (and in fact, amplifying it will just cause more problems and more distortion as it will have psychoacoustic effects due to stimulating other areas of āgoodā hearing). If I play tones or notes in one ear at regular volumes near the regions where the loss is the most, it just sounds massively wrong and distorted, multiple cents or semitones off, since I am relying on my acuity and brain to sort through the harmonics that I can actually still hear. And since it is non-linear as you described, thereās no real predictable signal processing Iāve tried when running subjective experiments on myself that can compensate gracefully for the issue, since it is very dynamic and can change completely even shifting down a few hz.
Iām entertaining the idea of octave transposition, although, I donāt know how well that would actually work in practice for true fidelity of music in my case specifically, which is/was my MAIN goal for hearing aids, and 90% of the reason I am considering to give them a try again. Many hearing aid algorithms mostly focus on reasonably correcting losses that are correctable, and on top of that providing some other āenhancementsā (perhaps in the harmonic octave of your hearing loss or key bands for speech intelligibility, namely in higher frequencies where consonant formant frequencies are critical) that will definitely help with things like speech intelligibility but in my opinion disfavourably imbalance the tonal balance of music. For example with my loss at ~400-1200hz in my right ear, an octave up would be 800-2400hz. You can immediately see the problem, since the loss falls in multiple octaves, pushing everything up would still not account for my unfixable/less fixable issues within 800-1200hz region, but may help some things like speech or localisation/awareness. Similarly pushing everything down to 200-600 would also have some overlap. Maybe a compromise in my case could be had pushing 400-800hz down to 200-400hz and then pushing 800-1200 up to 1600-2400 which would essentially be the ābestā of both words- but from my understanding hearing aids donāt necessarily have the functionality to do this arbitrarily for any frequencies and itās typically only really use to transpose much higher frequencies to lower ones in the case of that typical sloping loss you usually see for the sake of speech intelligibility (which is not a massive problem for me). You also have to factor in, moving stimulus from one frequency region to another āgoodā one through transposition is also going to hurt tonality and oneās intelligibility at regions where your hearing is actually āgoodā, since all of this transposition is going to mask fundamentals that occur in those bands, so it is a trade off. I can see this trade off being reasonable if someone has massive problems with conversation and communication- but since I donāt have this issue yet, why would I want to needlessly use these āfeaturesā when they are not conductive to my goal of maximising fidelity? I think there are some other solutions to this, like crossfeed or cross hearing aids where they transform and play the band in the opposite ear- but I am conveniently cursed with a loss in my āgoodā opposite ear that have a harmonic overlap with the losses in my bad ear! Argh! If I lower the frequencies in my better left ear, it falls into critical region of 400-1200 which is already working on overdrive to compensate for the deficiencies in my right! I have no idea what to do, and pray for a cure or solution.
