The relative impact of generic head-related transfer functions on auditory speech thresholds: implications for the design of three-dimensional audio displays.
BACKGROUND
Auditory speech thresholds were measured in this study.


METHODS
Subjects were required to discriminate a female voice recording of three-digit numbers in the presence of diotic speech babble. The voice stimulus was spatialized at 11 static azimuth positions on the horizontal plane using three different head-related transfer functions (HRTFs) measured on individuals who did not participate in this study. The diotic presentation of the voice stimulus served as the control condition.


RESULTS
The results showed that two of the HRTFS performed similarly and had significantly lower auditory speech thresholds than the third HRTF. All three HRTFs yielded significantly lower auditory speech thresholds compared with the diotic presentation of the voice stimulus, with the largest difference at 60 degrees azimuth.


CONCLUSIONS
The practical implications of these results suggest that lower headphone levels of the communication system in military aircraft can be achieved without sacrificing intelligibility, thereby lessening the risk of hearing loss.
Arrabito
G R
GR
Defence and Civil Institute of Environmental Medicine, Toronto, Ontario, Canada. robbie@dciem.dnd.ca
McFadden
S M
SM
Crabtree
R B
RB
D000162:Acoustics / Q000295:instrumentation; D000328:Adult; D000337:Aerospace Medicine; D000401:Aircraft / Q000295:instrumentation; D000704:Analysis of Variance; D001309:Auditory Threshold; D001359:Aviation / Q000295:instrumentation; D003638:Deafness / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D013065:Speech Intelligibility / Q000502:physiology; D013647:Task Performance and Analysis; D013685:Telecommunications / Q000295:instrumentation*