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An Auditory Illusion of Proximity of the Source Induced by Sonic Crystals.

Spiousas I, Etchemendy PE, Vergara RO, Calcagno ER, Eguia MC - PLoS ONE (2015)

Bottom Line: This effect seems, at first, paradoxical to naïve listeners since the sonic crystal is an obstacle formed by almost densely packed cylindrical scatterers.The results of the acoustical measurements showed that, for a certain frequency range and region in space where the focusing phenomenon takes place, the sonic crystal induces substantial increases in binaural intensity, direct-to-reverberant energy ratio and interaural cross-correlation values, all cues involved in the auditory perception of distance.Consistently, the results of the psychophysical experiment revealed that the presence of the sonic crystal between the sound source and the listener produces a significant reduction of the perceived relative distance to the sound source.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Acústica y Percepción Sonora, Universidad Nacional de Quilmes, Bernal, Buenos Aires, Argentina.

ABSTRACT
In this work we report an illusion of proximity of a sound source created by a sonic crystal placed between the source and a listener. This effect seems, at first, paradoxical to naïve listeners since the sonic crystal is an obstacle formed by almost densely packed cylindrical scatterers. Even when the singular acoustical properties of these periodic composite materials have been studied extensively (including band gaps, deaf bands, negative refraction, and birrefringence), the possible perceptual effects remain unexplored. The illusion reported here is studied through acoustical measurements and a psychophysical experiment. The results of the acoustical measurements showed that, for a certain frequency range and region in space where the focusing phenomenon takes place, the sonic crystal induces substantial increases in binaural intensity, direct-to-reverberant energy ratio and interaural cross-correlation values, all cues involved in the auditory perception of distance. Consistently, the results of the psychophysical experiment revealed that the presence of the sonic crystal between the sound source and the listener produces a significant reduction of the perceived relative distance to the sound source.

No MeSH data available.


Related in: MedlinePlus

Binaural intensity BI (left), interaural cross-correlation IACC (center) and direct to reverberant ratio DRR (right) for one-third-octave noise bands.The top plots corresponds to the recordings made with the sonic crystal slab between the source and the receiver (condition with-SC) and the bottom plots to the room response (condition without-SC). The results were obtained along the symmetry axis with a perpendicular distance to the slab (a-d). The results for the BI and DRR are expressed in dB, while the IACC is plotted in non-dimensional units. The dashed black frame delimits the focalization region defined in Eq 1.
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pone.0133271.g002: Binaural intensity BI (left), interaural cross-correlation IACC (center) and direct to reverberant ratio DRR (right) for one-third-octave noise bands.The top plots corresponds to the recordings made with the sonic crystal slab between the source and the receiver (condition with-SC) and the bottom plots to the room response (condition without-SC). The results were obtained along the symmetry axis with a perpendicular distance to the slab (a-d). The results for the BI and DRR are expressed in dB, while the IACC is plotted in non-dimensional units. The dashed black frame delimits the focalization region defined in Eq 1.

Mentions: As we mentioned in the previous section, we selected three acoustical cues that have a proven or likely correlate with the auditory perception of distance: the binaural intensity (BI), the direct-to-reverberant energy ratio (DRR) and the interaural cross-correlation (IACC). The values of these magnitudes (derived from the recordings, as detailed in the Material and Methods section) are displayed in Fig 2 as columns, for the conditions with-SC (top) and without-SC (bottom). Within each plot, the acoustical cues are displayed as a function of the central frequency of the noise bands and the position along the central axis (a-d on Fig 1b). The most noticeable difference introduced by the sonic crystal is an increase of the magnitudes for a central region of the plot, corresponding to the negative-refraction focusing. Also note that the position of the maximum depends on the central frequency. At the beginning of the focusing region (0.89 kHz) the greatest increment occurs at position a (0.8 m from the speaker) and as the frequency is increased the maximum is shifted away from the SC, reaching points c and d at the ending of the focusing region (1.41 kHz).


An Auditory Illusion of Proximity of the Source Induced by Sonic Crystals.

Spiousas I, Etchemendy PE, Vergara RO, Calcagno ER, Eguia MC - PLoS ONE (2015)

Binaural intensity BI (left), interaural cross-correlation IACC (center) and direct to reverberant ratio DRR (right) for one-third-octave noise bands.The top plots corresponds to the recordings made with the sonic crystal slab between the source and the receiver (condition with-SC) and the bottom plots to the room response (condition without-SC). The results were obtained along the symmetry axis with a perpendicular distance to the slab (a-d). The results for the BI and DRR are expressed in dB, while the IACC is plotted in non-dimensional units. The dashed black frame delimits the focalization region defined in Eq 1.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519286&req=5

pone.0133271.g002: Binaural intensity BI (left), interaural cross-correlation IACC (center) and direct to reverberant ratio DRR (right) for one-third-octave noise bands.The top plots corresponds to the recordings made with the sonic crystal slab between the source and the receiver (condition with-SC) and the bottom plots to the room response (condition without-SC). The results were obtained along the symmetry axis with a perpendicular distance to the slab (a-d). The results for the BI and DRR are expressed in dB, while the IACC is plotted in non-dimensional units. The dashed black frame delimits the focalization region defined in Eq 1.
Mentions: As we mentioned in the previous section, we selected three acoustical cues that have a proven or likely correlate with the auditory perception of distance: the binaural intensity (BI), the direct-to-reverberant energy ratio (DRR) and the interaural cross-correlation (IACC). The values of these magnitudes (derived from the recordings, as detailed in the Material and Methods section) are displayed in Fig 2 as columns, for the conditions with-SC (top) and without-SC (bottom). Within each plot, the acoustical cues are displayed as a function of the central frequency of the noise bands and the position along the central axis (a-d on Fig 1b). The most noticeable difference introduced by the sonic crystal is an increase of the magnitudes for a central region of the plot, corresponding to the negative-refraction focusing. Also note that the position of the maximum depends on the central frequency. At the beginning of the focusing region (0.89 kHz) the greatest increment occurs at position a (0.8 m from the speaker) and as the frequency is increased the maximum is shifted away from the SC, reaching points c and d at the ending of the focusing region (1.41 kHz).

Bottom Line: This effect seems, at first, paradoxical to naïve listeners since the sonic crystal is an obstacle formed by almost densely packed cylindrical scatterers.The results of the acoustical measurements showed that, for a certain frequency range and region in space where the focusing phenomenon takes place, the sonic crystal induces substantial increases in binaural intensity, direct-to-reverberant energy ratio and interaural cross-correlation values, all cues involved in the auditory perception of distance.Consistently, the results of the psychophysical experiment revealed that the presence of the sonic crystal between the sound source and the listener produces a significant reduction of the perceived relative distance to the sound source.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Acústica y Percepción Sonora, Universidad Nacional de Quilmes, Bernal, Buenos Aires, Argentina.

ABSTRACT
In this work we report an illusion of proximity of a sound source created by a sonic crystal placed between the source and a listener. This effect seems, at first, paradoxical to naïve listeners since the sonic crystal is an obstacle formed by almost densely packed cylindrical scatterers. Even when the singular acoustical properties of these periodic composite materials have been studied extensively (including band gaps, deaf bands, negative refraction, and birrefringence), the possible perceptual effects remain unexplored. The illusion reported here is studied through acoustical measurements and a psychophysical experiment. The results of the acoustical measurements showed that, for a certain frequency range and region in space where the focusing phenomenon takes place, the sonic crystal induces substantial increases in binaural intensity, direct-to-reverberant energy ratio and interaural cross-correlation values, all cues involved in the auditory perception of distance. Consistently, the results of the psychophysical experiment revealed that the presence of the sonic crystal between the sound source and the listener produces a significant reduction of the perceived relative distance to the sound source.

No MeSH data available.


Related in: MedlinePlus