Subjective Assessments of Real-Time Room Dereverberation and Loudspeaker Equalisation Panagiotis Hatziantoniou and John Mourjopoulos AudioGroup, WCL Department of Electrical and Computer Engineering University of Patras, Greece John W. Worley
Slide 2 of 13 Introduction To perceptual assess room deverberation. Using, Complex Smoothed room transfer functions (RTF) -v- loudspeaker equalisation. Measuring multi-dimensional sound quality attributes. F Low-frequency spectral balance. F High-frequency spectral balance. F Phase clarity. F Overall sound quality. F Room size. F Source distance.
Slide 3 of 13 Method: Anechoic inverse filter design Presentation, free from loudspeaker response coloration.
Slide 4 of 13 Method: Complex Smoothed inverse filter design Presentation, free from loudspeaker and RTF coloration.
Slide 5 of 13 Inverse filtering using smoothed filters from: “Results for Room Acoustics Equalisation Based on Smoothed Responses” Panagiotis D. Hatziantoniou and John N. Mourjopoulos,114th AES Convention, Amsterdam, March 2003 time domain frequency domain modification compensation
Slide 6 of 13 Test Rooms L: 7.15m X W: 4.60m X H: 2.90m. RT = sec (frequency averaged). L: 10.20m X W: 7.05m: X H:2.65m RT = 1.1 sec (frequency averaged). Room 1 Laboratory/Listening room Room 2 Classroom
Slide 7 of 13 2I-multi-AFC task. 8 Subjects. Stimuli Music Speech Castanets Snare Exp. Conditions On-filter -v- Off-filter presentation Anechoic -v- Smoothed filter 2 loudspeaker pairs 2 rooms Subjective assessment
Slide 8 of 13 Results: Room 1
Slide 9 of 13 Results: Room 2
Slide 10 of 13 Smoothed filter rated higher than anechoic: High-frequency spectral balance, phase clarity, overall sound quality, & room size. Listener position = non.sig. Sig. effect of room: High-frequency spectral balance, phase clarity, & overall sound quality Sig. effect of loudspeaker: Low-frequency spectral balance. Results: MANOVA & ANOVA
Slide 11 of 13 Conclusions Complex smooth filtering is not listener location specific A preference for Complex smooth filtering shown in: Temporal distinctiveness Mid- to high-frequency spectral balance Reduces reverberance Complex smooth filtering has more effect in acoustically poor room than optimum listening room. Listeners prefer good loudspeakers over poorer loudspeakers in terms of low-frequency spectral balance. Agreement with objective measures. Successful measure of multi-dimensional sound quality attributes.
Slide 12 of 13 Future work Compare filtering methods to commercial dereverberation DSP techniques (ie parametric equalisation). Measure and test Complex smooth filtering in a multi-purpose hall. Reduce the subjective measurement variables. Separately test the temporal and magnitude effect of Complex Smooth dereverberation.
AudioGroup, WCL Department of Electrical and Computer Engineering University of Patras, Greece