Of course I don’t have any experience in doing this. But this coming June when I get the new firmware update for the OPNs, for sure I’m going to ask the audi to implement the frequency shifting for me to try out and I’ll report back here my experience.
Hypothetically speaking, because I don’t have any experience in this, of course, I think frequency shifting by compressing the frequency ranges from a wider range into a narrower range equally (say between 250Hz-8KHz to 250Hz-2KHz) would not be desirable, especially if the compression is linear, because you basically lose the authenticity of the sound signal. Maybe there’s a non-linear type compression (maybe logarithmic???) that preserve the lows and mids to be almost as is, and perhaps between 1-2KHz range the compression is logarithmically more progressive, then it’d be not too bad.
But I think the transpose and merge approach by Oticon with their Speech Rescue LX (cut out a chunk at the high end and transpose that chunk down in the mid range and simply merge that chunk with what’s already there) will probably preserve the authenticity of the sound the best because you’ll hear the same information in your audible range and only additional information on top that you didn’t hear before but now you do. Essentially it’s “hear the same and more now” instead of “hear similar but different” now.