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. 2021 Jun 2:12:656052.
doi: 10.3389/fpsyg.2021.656052. eCollection 2021.

Investigation of an MAA Test With Virtual Sound Synthesis

Ruijie Meng  1   2 , Jingpeng Xiang  1   2 , Jinqiu Sang  1   2 , Chengshi Zheng  1   2 , Xiaodong Li  1   2 , Stefan Bleeck  3 , Juanjuan Cai  4 , Jie Wang  5
Affiliations

Investigation of an MAA Test With Virtual Sound Synthesis

Ruijie Meng et al. Front Psychol. .

Abstract

The ability to localize a sound source is very important in our daily life, specifically to analyze auditory scenes in complex acoustic environments. The concept of minimum audible angle (MAA), which is defined as the smallest detectable difference between the incident directions of two sound sources, has been widely used in the research fields of auditory perception to measure localization ability. Measuring MAAs usually involves a reference sound source and either a large number of loudspeakers or a movable sound source in order to reproduce sound sources at a large number of predefined incident directions. However, existing MAA test systems are often cumbersome because they require a large number of loudspeakers or a mechanical rail slide and thus are expensive and inconvenient to use. This study investigates a novel MAA test method using virtual sound source synthesis and avoiding the problems with traditional methods. We compare the perceptual localization acuity of sound sources in two experimental designs: using the virtual presentation and real sound sources. The virtual sound source is reproduced through a pair of loudspeakers weighted by vector-based amplitude panning (VBAP). Results show that the average measured MAA at 0° azimuth is 1.1° and the average measured MAA at 90° azimuth is 3.1° in a virtual acoustic system, meanwhile the average measured MAA at 0° azimuth is about 1.2° and the average measured MAA at 90° azimuth is 3.3° when using the real sound sources. The measurements of the two methods have no significant difference. We conclude that the proposed MAA test system is a suitable alternative to more complicated and expensive setups.

Keywords: VBAP; localization acuity; the frontal MAA; the lateral MAA; virtual sound synthesis.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
The VBAP system configuration. (A) The configuration of the frontal MAA measurement experiment; (B) The configuration of the lateral MAA measurement experiment.
Figure 2
Figure 2
The verification system configuration. (A) The configuration of the frontal MAA measurement experiment (0° azimuth), the angle ϕ= ±1°, ±2°, ±4 °, ±8°; (B) The configuration of the lateral MAA measurement experiment (90° azimuth), the angle ϕ= ±1°, ±2°, ±4 °, ±8°, ±15°.
Figure 3
Figure 3
Comparison of the results of the two methods. (A) The results of the frontal MAA measurement experiment; (B) The results of the lateral MAA measurement experiment.
Figure 4
Figure 4
The percentage of correct answers fitted by psignifit function in the baseline (dash line) and the VBAP method (dash-dot line). (A) The results of the front MAA measurement experiment; (B) The results of the lateral MAA measurement experiment.
Figure 5
Figure 5
ITDs and ILDs as a function of the critical bands for the baseline method (solid line marked with the black star) and the VBAP method (solid line marked with the red circle). Left column, 0° azimuth of incidence; and the right column, 90° azimuth of incidence. The top and bottom rows show the results for the ITDs and ILDs, respectively.
See this image and copyright information in PMC

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