Mid-Term Review John W. Worley AudioGroup, WCL Department of Electrical and Computer Engineering University of Patras, Greece http://www.wcl.ee.upatras.gr/AudioGroup/

2.2 Reliability of auditory cues in multi-source scenarios Tasks 2.1 The precedence effect Franssen illusion 2.2 Reliability of auditory cues in multi-source scenarios Learning non-individualised HRTFs 2.3 Perceptual models of room reverberation with application to speech recognition Complex smoothed room responses Perceptual factors in room responses

Task 2.1 Franssen illusion Reverberant environments = cue to multiple directions. The precedence effect = stable directional percept. Franssen illusion (F.I.) Precedence effect. ITD/ILD dependant

Task 2.1 Franssen illusion Hypothesis Localisation requires transients. Signal spectral density. Room differences. ITD/ILD dependant. Solution Various onset transitions. Sinusoid & Harmonic complex’s. Large vs. small rooms At present: F.I. in reverberation chamber. No transition effect. Increasing spectral density = Increased localisability. F.I. dependant on poor stimuli localisability. Future: F.I. with Grouping cues?? USE loudspeakers Use s/p stereo file with one left channel and one right (F0=0) Compare with same files but from one loudspeaker

Task 2.2 Learning non-individualised HRTFs Cone-of-confusion MVP HRTFs Individual HRTFs

Task 2.2 Learning non-individualised HRTFs: Results Type – I (2 listeners) Type - II (3 listeners) Response bias significantly determines reversal type = No reversal predisposition. = Majority of front-to-back reversals.

Task 2.3 Complex Smoothing Room Impulse Response (RIR): time domain frequency domain Original RIR Smoothed

perceptual smoothing profiles Start with a “smoothed” room response Use smoothing based on perception variable spectral resolution variable frequency-dependent windowing Employ “room masking models”

Task 2.3 Inverse filtering using smoothed filters time domain frequency domain modification compensation from: “Results for Room Acoustics Equalisation Based on Smoothed Responses” Panagiotis D. Hatziantoniou and John N. Mourjopoulos,114th AES Convention, Amsterdam, March 2003

Task 2.3 Smoothed filters physical metrics Tests in 6 rooms of Volume 60m3 – 11000m3 EDT reduced by up to 0,5 sec C80 improves by up to 5 dB D50 improves by up to 20% Spectral deviation is reduced up to 4 dB from: “Results for Room Acoustics Equalisation Based on Smoothed Responses” Panagiotis D. Hatziantoniou and John N. Mourjopoulos, 114th AES Convention, Amsterdam, March 2003

Task 2.3 Perceptual factors in room responses Real-time perception test. Various stimuli types (steady-state & transients). Assess multiple perceptual factors.

Task 2.3 Perceptual factors in room responses Source width. Source distance. Envelopment.

Task 2.3 Perceptual factors in room responses Anchor end-points with illustrative demonstrations and explanation. Results subjected to factor analysis

Perceptual factors in room responses (2.3). Future work Perceptual factors in room responses (2.3). ITD/ILD plausibility cues (2.1, 2.2). The combination of the cues is still debated. Use F0 grouping with FI for hierarchy of cues (2.2).

Department of Electrical and Computer Engineering AudioGroup, WCL Department of Electrical and Computer Engineering University of Patras, Greece http://www.wcl.ee.upatras.gr/AudioGroup/ …. Thank you very much...