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Binaural and Spatial Hearing Group. Learning the cues associated with non-individualised HRTFs. John Worley and Jonas Braasch. Binaural and Spatial Hearing Group. Head-Related Transfer Functions. Binaural and Spatial Hearing Group. Individual Differences in HRTFs. Highly idiosyncratic.
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Binaural and Spatial Hearing Group Learning the cues associated with non-individualised HRTFs John Worley and Jonas Braasch
Binaural and Spatial Hearing Group Head-Related Transfer Functions
Binaural and Spatial Hearing Group Individual Differences in HRTFs • Highly idiosyncratic. • Differences in HRTF magnitude due to differences in the size and shape of pinnae. • Inter-subject differences in level as much as 28 dB (Wightman & Kistler, ‘89a).
Binaural and Spatial Hearing Group Using Non-Individualised HRTFs • Binaural cues cue multiple locations. • Cones of confusion lead to reversal errors. • Non-individualised HRTFs result in a 3-fold increase in reversals over individualised HRTFs.
Binaural and Spatial Hearing Group Learning non-individualised HRTFs • Listeners adapt to long-term pinna modifications (Hofman et al, ’98). • Scaling non-individualised HRTFs improves localisation (Middlebrooks, ‘99). • Localisation is unaffected by smoothing HRTFs (Kulkarni & Colburn, ’98). • Visual system calibrates auditory input • Early-blind listeners (Zwiers & Van Opstal, ’01). • Compressed visual space compresses auditory space (Zwiers,’03).
Binaural and Spatial Hearing Group Methodology • Headphone-based azimuth localisation of scrambled noise. • HRTFs from prototype Neumann KU80 (pinna molded from average pinna). • 12 possible locations, surrounding the listener. • Instructed to respond to auditory event. • Responses recorded via GELP method (Gilkey et al 1995). • Test auditory localisation over time: • Day 1 = Auditory alone • Day 1 to 9 = Auditory location cued by visual stimuli • Day 10 = Auditory alone
330° Binaural and Spatial Hearing Group Methodology - Testing X
210° Binaural and Spatial Hearing Group Methodology - Training
Results Rear Rear
Results Rear Rear Perfect localisation
Results Results Rear Rear Rear Rear Front-to-back mislocalisation
Results Day 1- Testing • Responses clustered in the rear hemisphere.
Results Training Type – I (2 listeners) Type - II (3 listeners) • Response bias
Results All Days- Testing • Majority of front-to-back reversals. • No reduction in reversals as a function of time.
Results All Days- Testing Type - II Type - I Type – I = No reversal predisposition. Type- II = Majority of front-to-back reversals. Response bias significantly determines reversal type
Conclusions • Listeners display a response bias. • Response bias determines reversal type. • Overall, • Non-sig. reduction in reversals over training period. • Why?, • Difference between passive -v- dynamic listening. • Individualised head -v- dummy head.