The effect of frequency-dependent microphone directionality on horizontal localization performance in hearing-aid users.
Frequency-dependent microphone directionality alters the spectral shape of sound as a function of arrival azimuth. The influence of this on horizontal-plane localization performance was investigated. Using a 360 degrees loudspeaker array and five stimuli with different spectral characteristics, localization performance was measured on 21 hearing-impaired listeners when wearing no hearing aids and aided with no directionality, partial (from 1 and 2 kHz) directionality, and full directionality. The test schemes were also evaluated in everyday life. Without hearing aids, localization accuracy was significantly poorer than normative data. Due to inaudibility of high-frequency energy, front/back reversals were prominent. Front/back reversals remained prominent when aided with omnidirectional microphones. For stimuli with low-frequency emphasis, directionality had no further effect on localization. For stimuli with sufficient mid- and high-frequency information, full directionality had a small positive effect on front/back localization but a negative effect on left/right localization. Partial directionality further improved front/back localization and had no significant effect on left/right localization. The field test revealed no significant effects. The alternative spectral cues provided by frequency-dependent directionality improve front/back localization in hearing-aid users.
Keidser
Gitte
G
National Acoustic Laboratories, Chatswood, Australia. gitte.keidser@nal.gov.au
O'Brien
Anna
A
Hain
Jens-Uwe
JU
McLelland
Margot
M
Yeend
Ingrid
I
D000161:Acoustic Stimulation; D000368:Aged; D000369:Aged, 80 and over; D000669:Amplifiers, Electronic; D005260:Female; D006310:Hearing Aids; D006312:Hearing Loss, Bilateral / Q000534:rehabilitation; D006801:Humans; D008297:Male; D008875:Middle Aged; D019986:Persons with Hearing Disabilities / Q000534:rehabilitation*; D011474:Prosthesis Design / Q000295:instrumentation*; D013017:Sound Localization; D013018:Sound Spectrography; D013067:Speech Perception