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Reaching nearby sources: comparison between real and virtual sound and visual targets.

Parseihian G, Jouffrais C, Katz BF - Front Neurosci (2014)

Bottom Line: The current study concerns localization and pointing accuracy by examining source positions in the peripersonal space, specifically those associated with a typical tabletop surface.Results show no effect on the reporting hand with azimuthal errors increasing equally for the most extreme source positions.Various potential reasons for this discrepancy are discussed with several proposals for improving distance perception in peripersonal virtual environments.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Mécanique et d'Informatique pour les Sciences de l'Ingénieur, LIMSI - CNRS, Universite Paris Sud Orsay, France.

ABSTRACT
Sound localization studies over the past century have predominantly been concerned with directional accuracy for far-field sources. Few studies have examined the condition of near-field sources and distance perception. The current study concerns localization and pointing accuracy by examining source positions in the peripersonal space, specifically those associated with a typical tabletop surface. Accuracy is studied with respect to the reporting hand (dominant or secondary) for auditory sources. Results show no effect on the reporting hand with azimuthal errors increasing equally for the most extreme source positions. Distance errors show a consistent compression toward the center of the reporting area. A second evaluation is carried out comparing auditory and visual stimuli to examine any bias in reporting protocol or biomechanical difficulties. No common bias error was observed between auditory and visual stimuli indicating that reporting errors were not due to biomechanical limitations in the pointing task. A final evaluation compares real auditory sources and anechoic condition virtual sources created using binaural rendering. Results showed increased azimuthal errors, with virtual source positions being consistently overestimated to more lateral positions, while no significant distance perception was observed, indicating a deficiency in the binaural rendering condition relative to the real stimuli situation. Various potential reasons for this discrepancy are discussed with several proposals for improving distance perception in peripersonal virtual environments.

No MeSH data available.


Related in: MedlinePlus

Experimental setup. θt indicates the source position in the subjects head coordinate system.
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Figure 1: Experimental setup. θt indicates the source position in the subjects head coordinate system.

Mentions: The experimental setup used for both experiments consists of a semicircle platform of 1 m radius. It contained 35 sound sources distributed on five semi-circular rows spaced by 13 cm (radii at: 33, 46, 59, 72, and 85 cm); each row contained seven sources spaced by 30° (Figure 1). For the real sound condition, the sources comprised 35 small loudspeakers (ref: CB990, 8 Ohms, 3 Watt) placed under an acoustically transparent grid. Acoustically absorbing foam covered the mounting board between loudspeakers. Subjects were seated on a swivel chair with their head placed over the center of the semi-circle and at a height of 65 cm. Each loudspeaker was oriented to the subject's head in order to avoid loudspeaker directivity variations. All sources were equalized to present the same spectral response (speakers responses were flattened with twelve cascaded biquad filters) and level calibrated at the center of the listening head position (± 1 dB SPL). The spectral equalization suppressed potential supplementary localization cues and learning effects for a given loudspeaker. The loudness equalization suppressed the distance attenuation intensity cue so as to avoid potential relative judgments and to place the listener in an unfamiliar condition (the subject doesn't know the source and its “natural” level) as in Brungart et al. (1999).


Reaching nearby sources: comparison between real and virtual sound and visual targets.

Parseihian G, Jouffrais C, Katz BF - Front Neurosci (2014)

Experimental setup. θt indicates the source position in the subjects head coordinate system.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4151089&req=5

Figure 1: Experimental setup. θt indicates the source position in the subjects head coordinate system.
Mentions: The experimental setup used for both experiments consists of a semicircle platform of 1 m radius. It contained 35 sound sources distributed on five semi-circular rows spaced by 13 cm (radii at: 33, 46, 59, 72, and 85 cm); each row contained seven sources spaced by 30° (Figure 1). For the real sound condition, the sources comprised 35 small loudspeakers (ref: CB990, 8 Ohms, 3 Watt) placed under an acoustically transparent grid. Acoustically absorbing foam covered the mounting board between loudspeakers. Subjects were seated on a swivel chair with their head placed over the center of the semi-circle and at a height of 65 cm. Each loudspeaker was oriented to the subject's head in order to avoid loudspeaker directivity variations. All sources were equalized to present the same spectral response (speakers responses were flattened with twelve cascaded biquad filters) and level calibrated at the center of the listening head position (± 1 dB SPL). The spectral equalization suppressed potential supplementary localization cues and learning effects for a given loudspeaker. The loudness equalization suppressed the distance attenuation intensity cue so as to avoid potential relative judgments and to place the listener in an unfamiliar condition (the subject doesn't know the source and its “natural” level) as in Brungart et al. (1999).

Bottom Line: The current study concerns localization and pointing accuracy by examining source positions in the peripersonal space, specifically those associated with a typical tabletop surface.Results show no effect on the reporting hand with azimuthal errors increasing equally for the most extreme source positions.Various potential reasons for this discrepancy are discussed with several proposals for improving distance perception in peripersonal virtual environments.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Mécanique et d'Informatique pour les Sciences de l'Ingénieur, LIMSI - CNRS, Universite Paris Sud Orsay, France.

ABSTRACT
Sound localization studies over the past century have predominantly been concerned with directional accuracy for far-field sources. Few studies have examined the condition of near-field sources and distance perception. The current study concerns localization and pointing accuracy by examining source positions in the peripersonal space, specifically those associated with a typical tabletop surface. Accuracy is studied with respect to the reporting hand (dominant or secondary) for auditory sources. Results show no effect on the reporting hand with azimuthal errors increasing equally for the most extreme source positions. Distance errors show a consistent compression toward the center of the reporting area. A second evaluation is carried out comparing auditory and visual stimuli to examine any bias in reporting protocol or biomechanical difficulties. No common bias error was observed between auditory and visual stimuli indicating that reporting errors were not due to biomechanical limitations in the pointing task. A final evaluation compares real auditory sources and anechoic condition virtual sources created using binaural rendering. Results showed increased azimuthal errors, with virtual source positions being consistently overestimated to more lateral positions, while no significant distance perception was observed, indicating a deficiency in the binaural rendering condition relative to the real stimuli situation. Various potential reasons for this discrepancy are discussed with several proposals for improving distance perception in peripersonal virtual environments.

No MeSH data available.


Related in: MedlinePlus