SHHH sounds are high frequency sounds. It appears that you were able to manipulate the attack and release time of the aids. This is how much time it takes for the compression to attack or activate and release or de-activate. but if you have words that contains a mixture of high frequency and low frequency sounds then it appears that there can be an overlapping of sounds. as the low frequencies that are not compressed is being sent to the ear before the aid finished processing the high frequency sounds that came in earlier.
Can’t remember if ipfg makes this adjustable. looking at the old ipfg I can’t find it to be adjustable. possibly something that can be adjusted indirectly. but you can test this by eliminating all compression by setting the compression ratio to 1. If you don’t hear the problem after the adjustment then that’s it.
but I thought this all was an issue with sound recover. maybe it’s doing something similar in that the application of it has an “attack” and “release” time. I would be surprised if phonak made the attack and release time of sound recover adjustable. once again this can be tested by turning it off and if you don’t hear the issue then that’s it.