Got Tympan working, seek sound improvement tips

I got my Tympan working with the “Basic Gain” example. Thanks for the help from here and other places.

It’s promising: I can use it as a hearing aid out of the box, although the sound quality makes it difficult to understand speech sometimes.

What would be the easiest and best sound quality improvements?

Better microphone? Looks like @chipaudette did a bunch of testing on the internal mic, so replacements might need some careful selection to provide better sound. Any suggestions for a better microphone?

Better ear pieces? Suggestions for better ear pieces?

A different Tympan example? I see Chip has provided several others, besides the Basic Gain…

Anything else?

(Background: I’ve used expensive medical hearing aids and a couple of “hearing amplifiers”, including the sadly discontinued Bose Hearphones (which had the best sound, but died in a year). Hoping Tympan will become a usable replacement as well as an interesting experiment.)