Read Chasin articles. 

I think it's useful to consider the different goals of hearing-aid processing for speech vs. music. For speech, the goal of advanced signal processing is typically to maximize intelligibility, which does not always lead to the best sound quality (i.e. there is a trade-off between audibility and distortion -- see research by Arehart, Kates, and Souza for more on this). For music, quality is most important, and quality is often best with the closest possible fidelity to the original signal. Therefore, I think music processing in hearing aids should do as little as possible to the signal while providing amplification when needed. In addition to turning off advanced features like feedback and noise cancellation, music quality can be improved by using linear processing instead of dynamic-range compression, especially compared to fast compression. These are just software changes that can improve quality, assuming that the signal is not already distorted by having a maximum input level that is too low on the front end of the hearing aid (and as Himanshu already mentioned, this is frequently discussed in Chasin's work).

Than k you for your comments. I have not got my draft review document ready to post, so Ill just say some of these issues Ive already explored to some degree.It would i think  be useful to post an early draft on researchgate when I think it has reached a minimal threshold for being a helpful trigger for critique and response and thus a a contribution to this discussion.

I can see that you (appear to) come mainly from a hearing/speech orientation-and thats not a problem at all-however the interesting aspects of my reasonably extensive lit review and analysis is that most hearing bodies are focussed more on avoiding hearing loss than on enhancing the quality of life of those with aids for what ever reason. An interesting sidelight is that those who used analog aids almost uniformly reported dissapointment with the current digital basis and the design factors adopted-and some are avidly searching for these old aids for their musical listening to this day! We can learn from this consumer response...

I am struck by the number of times a very minimal referral to spatial cues is mentioned-but not followed up. As far as i have yet found out only the use of a CI+an HA in the opposite ear has had much attention. another comment (from virtually every performer I have spoken to in my explorations before making a  research proposal, is the complaints over the whistles of hearing aids in intervals in the music in recital halls! (as user strive to get an amplification and setting balance)..and the complaints of virtually every attempted use of the hearing aid coil settings..including my own.The enhancement of aids for the users is also likely to -at the same time - add value to all the other members of the music audiences and performers thereby!

I am of course fully aware of Chasin's work, and i have read most of it and that of his collaborators. I am not aware of Himanshu, Aregart, Kates and Souza..and so a few references/urls would be gratefully received

I also have a physics and an engineering background, and soem engagement with psychoacoustics (at a non professional levels of skill), but signal processing is a clear and present tool that has yet to be turned to fully effective dual speech/music use in a number of ways. I am looking at that and am most surprised to find it not an issue in ISMIR! the natural place to discuss it in my still tentative view.

Fortunately I live in Melbourne Australia so a number of the specialists in CI bionic ear and bionic eye-and indeed adaptive algorithm HAs are all within half an hours motorcycle ride... and Im using this accessibility!

Hello,

this is an interesting question regarding the fact of technology shift we got through. I have a moderate conductive hearing loss and experience of using both analog and digital hearing aids and got through a disappointment of using digital technology in the hearing aids but 2 years ago I was implanted with a bone-conduction hearing implant and digital technology works significantly better in these devices. As I am an otorhinolaryngologist by profession and involved more in the clinical aspects of audiology my patients repeatedly come back with these observations. Fraction of patients also claim that even quality of speech is better with analog HAs. Also, isn`t type of compression different if we talk about different types of HL?

A few things to keep in mind are that music appreciation and music perception are different. So is the aim to improve perceptual accuracy for music (i.e. pitch perception, psychoacoustic tasks, recognising instruments etc) - OR is it music appreciation (i.e. sound quality, enjoyment of music)? They are not the same, and research I've done and others (e.g. Kate Gfeller) has shown only weak correlations between accuracy & enjoyment.

Also keep in mind that music has so many different styles. So to 'give a better experience' for music may require different things for different styles.

Also keep in mind the level of hearing loss (& type of hearing loss) of your HA wearer. For example, Brian Moore & colleagues have shown that a moderate or worse sensorineural hearing loss leads to wider auditory filter bandwidths that would then affect frequency resolution and specificity. So in addition to the technology in the HA, you have to also consider the physiological changes in the cochlea, and the resulting psychoacoustic impact.

If you haven't already, talk to Hugh McDermott down there at the Bionic Institute for the signal processing side of things, and Colette McKay for the psychophysics. 

The literature related to CI+HA can't really be directly applied to HA only - as usually in bimodal stimulation (i.e. HA with CI), for the conventional CI user, the HA is fit to 'work with' the CI - i.e. more low frequency amplification, loudness balancing etc. And the hearing thresholds & configuration of the hearing loss for someone using bimodal (or EAS) stimulation would be somewhat different to your 'run of the mill' HA user.

I really must congratulate all the responders to my question. Every one is thoughtful and  a contribution that one can really use and learn from. Im pleased I did not post my current working review draft, as i suspect that some of the suggestion made might not have been made!

The answer the last entry, Valerie, at this point it is the differences between enjoyment and/or satisfaction with different types of music that i targeting with the same subject each time. The key issue for me at present id Differences in single subjects to different musical types(which of course have their own features and characteristics of all kinds)-and perceptual accuracy will matter to some but not others:Im well aware of the differences between enjoyment/taste (familiarity impacts etc) and accuracy (and indeed frequency range) of reproduction from various sources, and also the sensitivities to distortion that seem to matter to all those I have checked with to see if my experience ( with progressive hearing loss notwithstanding) was repeated: purely a convenience sample at this point of course.

On specifics, it depends on whether or not I get a small seeding grant: if I do Ill be chasing up same aspects and delaying others(the signal processing will be done later for example), if I do not I'll be proceeding at a slower rate over a wider span-and DSp issues will be to the fore, And yes I have joined ISMIR!

Id warmly welcome URls to (or Even Better .pdfs), of the articles that all these expert responders feel I should read..