Oh, interesting and strange. Sometimes it feels we know so much in this modern world and then suddenly we’re reminded of what we DON’T know.
What area are you in? It may be worth having a full auditory processing assessment with an audiologist who does that if you can find one nearby.
Evidence for the efficacy of auditory training is still a bit weak overall. For children with auditory processing issues I believe the most powerful emerging intervention is on-ear remote microphone technology (put a microphone on the speaker and pipe it right into the child’s ears with devices that essentially look like hearing aids). This is convenient, because it was something we were doing in classrooms anyway to provide support, but it turns out that in addition to increasing the signal-to-noise ratio and helping them out directly with their difficulty, it actually appears to have long-term therapeutic effects whereby after 1-2 years of semi-consistent daily classroom use there are lasting improvments in the auditory system when use is discontinued, as measured by EEG as well as behaviourally, and improvements seem to generalize well. This makes sense from a brain function perspective–neurons that fire together wire together, and by providing a consistent, clear speech signal the pathways in the brain dedicated to processing that signal become stronger/fire in better synchrony.
Auditory training for specific auditory skills is. . . a pathway that is still being pursued and something many clinicians are enthusiastic about with limited scientific evidence. I think that there is reasonable indication for benefit in certain circumstances right now. For example, in the case of amblyaudia where one ear is ‘weak’ in dichotic listening tasks, this seems to be affected relatively quickly with training to good benefit. On the other hand, there are a lot of other attempts at targetted auditory training where there is evidence that the individual gets better at the particular game (or whatever) that they are playing, but it doesn’t appear to generalize to other aspects of life. In some ways I also think that specific skills training might be a bit of a red herring: When we test for auditory processing disorder we select a handful of tests that assess a small subset of our auditory skills. It seems likely that if a couple of those are disordered there may well be other untested skills that are also disordered. Trying to boost each skill individually with artificial stimuli may not make practical sense compared to trying to just using the target complex auditory stimulus of speech.
So that is my perhaps-unasked-for rundown of the current state of auditory training, and keep in mind that my opinion is my own and there is actually no gold standard for diagnosing and treating auditory processing disorder yet, although at this point there is a general consensus that it is a real thing. Clinicians and scientists are still arguing and researching. It’s a new area where clinical practice is running a bit further ahead of scientific evidence than we might prefer. But I also have a heavy scientific research background and I can sometimes be more demanding and skeptical than other in my field. Clinical audiologists are eager to help the person in front of them.
Your case is a bit further complicated by the facts that: A) You already have a unilateral hearing loss, though mild, which is reason enough to consider your hearing a bit disordered and would be expected to result in speech-in-noise difficulty all by itself, and B) your current symptoms are acquired from a new disease rather than developmental in childhood, which is what a lot of the literature is focussing on right now, Plus, long covid and may well be associated with other cognitive impacts.
As an aside, this is anecdotal, but a fair number of my concussion patients (who often struggle with sound and noise sensitivity and auditory processing issues of their own) report that they have specific difficulty with recorded speech while live speech is okay. I have no idea why this is. There appears to be some way in which the post-concussion brain is more sensitive to the distortions associated with recorded audio. I’ve heard other clinicians mention it, but I don’t think it is something under investigation right now.
What does all of this mean for you? I think it is just a caution that it may not be worth pursuing anything that might present a financial burden to you. Nothing in current auditory training is risky or damaging, apart from using up your time and money. So as long as you feel that you are up for taking a chance you can likely try anything, but if someone quotes you $10k for lengthy training sessions I might hesitate, even if they are enthusiastic about it. (Or insert whatever amount of money becomes difficult for you rather than acceptible experiment for your disposable income.)
And then additionally, you can probably chase some of this on your own. You mentioned Nancy Drew audiobooks were fine. You can probably work on spending some time doing focussed listening at a comfortable but loud-ish volume, and up the difficulty over time. You can also be more aware of the ways in which distance and noise rapidly degrade a speech signal and that this might be impacting you, so organize your environment a bit to manage that.
Sorry again for the long post; it’s an area of interest for me.
. Now, along with massive deconditioning, I imagine I have a bit of “resulting damage” from all those years like how an organ gradually stop functioning and completely died last year. But, I can now slowly get better.