The Application and Practical Concerns of Advanced 
Hearing Aid Signal Processing Technologies to Enhance Cochlear Implants

King Chung1, Ph.D.; Fan-Gang Zeng2, Ph.D. and Susan Waltzman3, Ph.D. 

1 Purdue University, West Lafayette, IN, USA;
2 University of California, Irvine, CA, USA; 
3 New York University, New York, NY, USA

The purpose of this study was to investigate if applying hearing aid 
directional microphones and noise reduction algorithms as pre-processors
to cochlear implant speech processors can enhance speech understanding
and listening preference of cochlear implant users.  Hearing aid 
pre-processed speech materials were recorded when KEMAR was wearing 
a pair of 6-channel and a pair of 9-channel digital hearing aids and
sitting at the center of an 8-speaker array.  The hearing aids were
programmed to omni-directional microphone (Om), directional microphone (Dm),
and directional microphone plus noise reduction algorithms (Dm+NR). 
Cochlear implant users listened to the hearing aid pre-processed 
speech materials in sound field to simulate the use of hearing aids as
pre-processors to cochlear implants.  They repeated the words and ranked 
their listening preferences of the three experimental conditions.  The results 
and some practical concerns, e.g., where compression should be implemented,
will be discussed.