NOISE-REDUCTION WITH FM SYSTEMS IN FM EM MODE

Authors
Citation
Da. Fabry, NOISE-REDUCTION WITH FM SYSTEMS IN FM EM MODE, Ear and hearing, 15(1), 1994, pp. 82-86
Citations number
28
Categorie Soggetti
Otorhinolaryngology
Journal title
ISSN journal
01960202
Volume
15
Issue
1
Year of publication
1994
Pages
82 - 86
Database
ISI
SICI code
0196-0202(1994)15:1<82:NWFSIF>2.0.ZU;2-I
Abstract
Commercially available noise reduction hearing aids have failed to del iver improved speech recognition in noise over properly fit convention al devices under typical listening conditions (Fabry & Van Tasell, 199 0; Gabrielsson, Schenkman, & Hagerman, 1988; Tyler Q Kuk, 1989; Van Ta sell, Larsen, & Fabry, 1988). The primary factor related to this findi ng is that speech and noise are mixed at the input of a single microph one; spectral changes are applied equally to both speech and noise, an d the signal-to-noise ratio remains unchanged from unprocessed conditi ons. The purpose of this study was to evaluate a prototype frequency-m odulated (FM) auditory trainer that allowed use of a remote FM microph one and/or an ear level environmental microphone (EM). For each of fiv e subjects with moderate to severe sensorineural hearing loss, the fre quency response of the EM was configured either to match that of the F M response, or to provide a high-pass filter characteristic similar to a noise reduction hearing aid. Speech recognition threshold (SRT) tes ting in noise was measured for five test conditions: 1) FM only; 2) EM only with high-pass filter response (EM-HP); 3) EM only with ''standa rd'' response (EM-S) matched to FM; 4) FM/EM-HP combined mode; and 5) FM/EM-S mode. Results averaged across subjects indicated that SRTs for the FM only condition were 9 to 10 dB better than those for either EM only condition; data from the combined FM/EM-HP mode averaged 4 dB be tter than for FM/EM-S conditions.