1. Mid-Term Review John W. Worley AudioGroup, WCL
Department of Electrical and Computer Engineering
University of Patras, Greece

2. 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

3. 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

4. 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

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

6. 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.

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

8. 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”

9. 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

10. 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

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

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

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

14. 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).

15. Department of Electrical and Computer Engineering
AudioGroup, WCL
Department of Electrical and Computer Engineering
University of Patras, Greece
…. Thank you very much...