hoarse voice

[linear]

CIC normally have an  extra gain from 5 to 15 dB on high frequency 
( 2000-6000 Hz) caused by the deep insertion . Normally this phenomena 
is difficult to see with a real ear
Using an hearing aids there is always an alteration of the feedback 
voice-hear and, if there is an excess of power on high frequency, 
normally the patient increase the low frequency components of his voice 

I suggest you to do an audiometry in open field with hearing aids and 
verify if  high and low frequency are balanced 

You can also do  an experiment to reduce  high frequencies putting a 
very small piece of foam rubber in the  receiver's hole  and verifying 
the voice changing of your patient   

More information about CIC power increase are in "The Hearing Journal " 
of July 94 It 's one of the best works on CIC application

Send me an E mail if I've solved your problem
Sorry for English mistakes 

Luca Racca