1. Franssen illusion within large rooms John W. Worley AudioGroup, WCL Department of Electrical and Computer Engineering University of Patras, Greece http://www.wcl.ee.upatras.gr/AudioGroup/

2. Slide 2 of 17 Introduction Reverberant environments cue multiple directions. The precedence effect leads to a stable directional percept. Franssen illusion Precedence effect Plausibility hypothesis

3. Slide 3 of 17 Method Task = Indicate start and end stimuli location (Frontal hemisphere). Trials: sn - Across midline (-30º & +30º). n - Left movement (-75º to -15º). n- Right movement (+75º to +15º).

4. Slide 4 of 17  Transitions:  50msec  500msec  1000msec F2: Transitions TransitionSustain

5. Slide 5 of 17 F2 Method: Stimuli Virtual presentation with dummy-head HRTFs Rooms: Reverberation chamber and multi-purpose hall (AudiMax, RUB). 125Hz250Hz500Hz1000Hz2000Hz4000Hz 15.013.67.56.65.12.3 2.42.52.72.62.11.7 500Hz sinusoid (Hartmann & Rakerd, 1989) Harmonic complex’s, with 200Hz F0 (3, 5, and 7 harmonics). Rev - Audi -

6. Slide 6 of 17 F2 Results: Audimax Franssen illusion fails. Reverberation chamber Franssen illusion. Sig. effect of stimuli?? Overall, No effect of room or transition duration. Sig. effect of stimuli?? Reverberation chamberAudimax

7. Slide 7 of 17 F3 Method: Two large environments. 500Hz sinusoid. Transitions - 50msec, 500msec, 1000msec 4 sec sustain before transition. Transition Sustain

8. Slide 8 of 17 F3 Results: No effect of transition. Sig. Room Effect.

9. Slide 9 of 17 Exp: Localisation Azimuth localisation in the frontal plane. Multi-purpose hall & reverberation chamber. 500Hz tone & 7 component harmonic complex. 50msec, 500msec, 1000msec transitions. 2 sec duration, inc. transition.

10. Slide 10 of 17 Exp. Localisation: Results (500Hz) Very poor localisation in reverberation chamber

11. Slide 11 of 17 Exp. Localisation: Results (7-com harmonic) Similar localisation in reverberation chamber and the multi-purpose hall.

12. Slide 12 of 17 Conclusions F2: Differences in d’prime in reverberation chamber as function of stimuli. F3: FI with 500Hz tone in reverberation chamber. Not Audimax. Exp 3: Differences in localisation with room. Illusion related to effect of room acoustics on localisation ability (Blauert, 1974). Future work: At Patras, More subjects, different response technique. Increase transition range. Roles of ITD and/or ILD plausibility with grouping cues.

13. AudioGroup, WCL Department of Electrical and Computer Engineering University of Patras, Greece http://www.wcl.ee.upatras.gr/AudioGroup/