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Perception and evaluation of sound fields Hagen Wierstorf 1 , Sascha Spors 2 , Alexander Raake 1 1 Assessment of IP-based Applications, Technische Universitt Berlin 2 Institute of Communications Engineering, Universitt Rostock 12. September

SLIDE 1

Perception and evaluation of sound fields

Hagen Wierstorf1, Sascha Spors2, Alexander Raake1

1Assessment of IP-based Applications, Technische Universität Berlin 2 Institute of Communications Engineering, Universität Rostock

12. September 2012

SLIDE 2

Introduction

How to assess and model the perception of a sound field? Why to assess and model the perception of a sound field? This will be discussed with the example of localization

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SLIDE 3

Sound Field Synthesis

physically motivated synthesis

−2 −1 1 −2 −1 1 2 y/ m x/ m

loudspeaker spacing: 0.19 m virtual source

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SLIDE 4

Sound Field Synthesis

psychoacoustically motivated synthesis

−2 −1 1 −2 −1 1 2 y/ m x/ m

loudspeaker spacing: 0.41 m virtual source

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SLIDE 5

Localization within a sound field

listener experiments

−2 −1 1 −2 −1 1 2 y/ m x/ m

loudspeaker spacing: 0.41 m

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Localization within a sound field

definition

localization error := deviation of the direction of the auditory event from the direction of the sound event

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Localization within a sound field

binaural modelling

−2 −1 1 −2 −1 1 2 y/ m x/ m 0° 20° 40°

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SLIDE 8

Binaural synthesis

virtual sources

connection between sound field synthesis and psychoacoustics (Völk, 2008) dynamic binaural synthesis via head tracker transparent with individual HRTFs (Langendijk, 2000)

Völk et al. (2008), Simulation of wave field synthesis, Acoustics Langendijk und Bronkhorst (2000), Fidelity of three-dimensional-sound reproduction using a virtual auditory display, JASA

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SLIDE 9

Binaural synthesis

virtual sources

connection between sound field synthesis and psychoacoustics (Völk, 2008) dynamic binaural synthesis via head tracker transparent with individual HRTFs (Langendijk, 2000)

Völk et al. (2008), Simulation of wave field synthesis, Acoustics Langendijk und Bronkhorst (2000), Fidelity of three-dimensional-sound reproduction using a virtual auditory display, JASA

Wierstorf, Spors, Raake Perception of sound fields 12/09/12 5 / 13

SLIDE 10

Binaural synthesis

virtual sources

connection between sound field synthesis and psychoacoustics (Völk, 2008) dynamic binaural synthesis via head tracker transparent with individual HRTFs (Langendijk, 2000)

Völk et al. (2008), Simulation of wave field synthesis, Acoustics Langendijk und Bronkhorst (2000), Fidelity of three-dimensional-sound reproduction using a virtual auditory display, JASA

Wierstorf, Spors, Raake Perception of sound fields 12/09/12 5 / 13

SLIDE 11

Binaural synthesis

virtual sources

connection between sound field synthesis and psychoacoustics (Völk, 2008) dynamic binaural synthesis via head tracker transparent with individual HRTFs (Langendijk, 2000)

Völk et al. (2008), Simulation of wave field synthesis, Acoustics Langendijk und Bronkhorst (2000), Fidelity of three-dimensional-sound reproduction using a virtual auditory display, JASA

Wierstorf, Spors, Raake Perception of sound fields 12/09/12 5 / 13

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Binaural synthesis and localization

real vs. virtual sources

localization error is between 1◦-5◦ for the horizontal plane for real and virtual sources (Makous 1990, Hess 2004, Bronkhorst 1995, ...) it varies with different experimental methods (Majdak 2008) it is the same with individual HRTFs as for real sources, but slightly larger for non-individual HRTFs (Seeber 2003)

Makous and Middlebrooks (1990), Two-dimensional sound localization by human listeners, JASA Hess (2004), Influence of head-tracking on spatial perception, 117th AES Bronkhorst (1995), Localization of real and virtual sound sources, JASA Majdak et al. (2008), The Accuracy of Localizing Virtual Sound Sources: Effects of Pointing Method and Visual Environment, 124th AES Seeber (2004), Untersuchung der auditiven Lokalisation mit einer Lichtzeigermethode, Technische Universität München

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Localization of real and virtual sources

apparatus

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Localization of real and virtual sources

apparatus

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Localization of real and virtual sources

method

head-pointing method with laser pointer mounted on the head (Makous 1990) ⇒ listener has to face the source, smallest human lateralisation error (Mills 1958) ⇒ laser pointer gives visual feedback and enhances the cooperation with the motor system (Lewald 2000) white noise pulses 700 ms long, 300 ms pause 11 subjects, 11 loudspeakers 5 repetitons for each condition and loudspeaker position 3 conditions: real loudspeaker, anechoic HRTF, room HRTF

Makous and Middlebrooks (1990), Two-dimensional sound localization by human listeners, JASA Mills (1958), On the minimum audible angle, JASA Lewald et al. (2000), Sound localization with eccentric head position, Behav Brain Res

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Localization of real and virtual sources

room HRTFs

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SLIDE 17

Results

mean signed error + 95% confidence interval

−6◦ 0◦ 6◦ −6◦ 0◦ 6◦ φauditory event − φsound event −6◦ 0◦ 6◦ −45◦ −30◦ −15◦ 0◦ 15◦ 30◦ 45◦ φsound event

loudspeaker room HRTF anechoic HRTF

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SLIDE 18

Results

summary

Loudspeaker room HRTF anechoic HRTF unsigned error /◦ 2.4 ±0.59 1.5 ±0.26 2.0 ±0.56 standard deviation /◦ 2.2 ±0.15 2.4 ±0.28 3.8 ±0.30 time / s 3.5 ±0.65 3.7 ±0.55 5.5 ±1.72

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SLIDE 19

Results

summary

Loudspeaker room HRTF anechoic HRTF unsigned error /◦ 2.4 ±0.59 1.5 ±0.26 2.0 ±0.56 standard deviation /◦ 2.2 ±0.15 2.4 ±0.28 3.8 ±0.30 time / s 3.5 ±0.65 3.7 ±0.55 5.5 ±1.72

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Conclusion

Why to assess and model the perception of a sound field? Sound field synthesis methods are more psychoacoustically motivated than considered. Localization and coloration still not fully understand. How to assess and model the perception of a sound field? With binaural synthesis. full control of stimuli reaching the listener or a auditory model every position and loudspeaker array possible not fully transparent, but localization with anechoic HRTFs feasible

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SLIDE 21

Questions?

http://audio.qu.tu-berlin.de/

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