Use of Proximity Effect in Hearing Aid Microphones to Increase Telephone Intelligibility in Noise
Abstract
This thesis describes an experiment to test the use of the proximity effect to increase the intelligibility of telephone speech for hearing-aid wearers. NU-6 word lists were played through the equivalent of long-distance telephone lines with a standard Bell 500 handset, while Multi-Talker noise was played in the background at three different levels. The signals were picked up with one of three microphones placed by the ear of a dummy head: a first-order pressure-gradient microphone (bi-directional), a zero-order microphone (omni- directional), or one with order between zero and one (cardioid). The signal picked up by these microphones was recorded and played back to normal-hearing subjects through a modified hearing aid, while the Multi-Talker noise was played in the background. The pressure gradient microphones allowed significant better understanding of the telephone signal than did the pressure microphone and this difference was more pronounced at higher noise levels. The bidirectional and cardioid microphones did not provide significantly different scores at any noise level. It is argued that this similarity may be due to head effects reducing the pressure-gradient sensitivity of the microphones. The use of the proximity effect to enable hearing aids to pick up a telephone conversation while discriminating against background noise appears to be successful.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1988
- Accession Number
- ADA197311
Entities
People
- Kathryn R. Wilson
Organizations
- Pennsylvania State University