title: The relative impact of generic head-related transfer functions on auditory speech thresholds: implications for the design of three-dimensional audio displays.
abstract: 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.
authors.affiliation: Defence and Civil Institute of Environmental Medicine, Toronto, Ontario, Canada. robbie@dciem.dnd.ca
authors.forename: G R
authors.initials: GR
authors.lastname: Arrabito
authors.forename: S M
authors.initials: SM
authors.lastname: McFadden
authors.forename: R B
authors.initials: RB
authors.lastname: Crabtree
mesh_terms: 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*