Perception and evaluation of sound fields Hagen Wierstorf 1 , Sascha - PowerPoint PPT Presentation

Perception and evaluation of sound fields Hagen Wierstorf 1 , Sascha Spors 2 , Alexander Raake 1 1 Assessment of IP-based Applications, Technische Universität Berlin 2 Institute of Communications Engineering, Universität Rostock 12. September 2012

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 Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 1 / 13

Sound Field Synthesis physically motivated synthesis virtual source 1 loudspeaker spacing: 0 . 19 m 0 y / m − 1 − 2 − 2 − 1 0 1 2 x / m Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 2 / 13

Sound Field Synthesis psychoacoustically motivated synthesis virtual source 1 loudspeaker spacing: 0 . 41 m 0 y / m − 1 − 2 − 2 − 1 0 1 2 x / m Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 2 / 13

Localization within a sound field listener experiments 1 0 y / m − 1 loudspeaker spacing: 0 . 41 m − 2 − 2 − 1 0 1 2 x / m Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 3 / 13

Localization within a sound field definition localization error := deviation of the direction of the auditory event from the direction of the sound event Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 4 / 13

Localization within a sound field binaural modelling 1 0° 20° 40° 0 y / m − 1 − 2 − 2 − 1 0 1 2 x / m Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 4 / 13

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 12/09/12 Perception of sound fields 5 / 13

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 12/09/12 Perception of sound fields 5 / 13

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 12/09/12 Perception of sound fields 5 / 13

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 12/09/12 Perception of sound fields 5 / 13

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 , 117 th 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 , 124 th AES Seeber (2004), Untersuchung der auditiven Lokalisation mit einer Lichtzeigermethode , Technische Universität München Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 6 / 13

Localization of real and virtual sources apparatus Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 7 / 13

Localization of real and virtual sources apparatus Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 7 / 13

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 Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 8 / 13

Localization of real and virtual sources room HRTFs Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 9 / 13

Results mean signed error + 95 % confidence interval loudspeaker 6 ◦ 0 ◦ φ auditory event − φ sound event − 6 ◦ room HRTF 6 ◦ 0 ◦ − 6 ◦ anechoic HRTF 6 ◦ 0 ◦ − 6 ◦ − 45 ◦ − 30 ◦ − 15 ◦ 0 ◦ 15 ◦ 30 ◦ 45 ◦ φ sound event Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 10 / 13

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 Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 11 / 13

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 Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 11 / 13

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

Questions? http://audio.qu.tu-berlin.de/ Wierstorf, Spors, Raake 12/09/12 Perception of sound fields 13 / 13