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Binaural sound localizer for azimuthal movement detection based on diffraction.

Kim K, Choi A - Sensors (Basel) (2012)

Bottom Line: The gradient analysis of the ILD between the structured and unstructured microphone demonstrates the rotation directions as clockwise, counter clockwise, and no rotation of the sound source.Acoustic experiments with different types of sound source over a wide range of target movements show that the average true positive and false positive rates are 67% and 16%, respectively.Spectral analysis demonstrates that the low frequency delivers decreased true and false positive rates and the high frequency presents increases of both rates, overall.

View Article: PubMed Central - PubMed

Affiliation: Division of Electronics & Electrical Engineering, Dongguk University-Seoul, Seoul 100-715, Korea. kwkim@dongguk.edu

ABSTRACT
Sound localization can be realized by utilizing the physics of acoustics in various methods. This paper investigates a novel detection architecture for the azimuthal movement of sound source based on the interaural level difference (ILD) between two receivers. One of the microphones in the system is surrounded by barriers of various heights in order to cast the direction dependent diffraction of the incoming signal. The gradient analysis of the ILD between the structured and unstructured microphone demonstrates the rotation directions as clockwise, counter clockwise, and no rotation of the sound source. Acoustic experiments with different types of sound source over a wide range of target movements show that the average true positive and false positive rates are 67% and 16%, respectively. Spectral analysis demonstrates that the low frequency delivers decreased true and false positive rates and the high frequency presents increases of both rates, overall.

No MeSH data available.


(a) Theoretical spectral distribution of RDD structure. (b) Experimental spectral distribution of RDD structure.
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f8-sensors-12-10584: (a) Theoretical spectral distribution of RDD structure. (b) Experimental spectral distribution of RDD structure.

Mentions: The acoustically whitened signal based on the chamber transfer function is transmitted and recorded in five degree increments in order to generate the spectral distribution. From Equation (1), the theoretical spectral distribution for 360 degrees is illustrated in Figure 8(a), which denotes the significant level reduction at the elevated barrier height. It should be noted that the height of the barrier is proportional to the angle of the structure. In the vicinity of high angle, the spectrum is covered by low level values in particular for high frequency range. Also, the high level values become narrower for the low frequency range. The experimentally measured spectral distribution is exhibited in Figure 8(b) with 128 sample window length and ensemble averaged in order to reduce the variance of the signal. The spline interpolation with five times grid expansion in angle and frequency is used for Figure 8 in order to draw the smooth contours representing the comprehensive characteristics of the spectrum field. Unlike the theoretical result, the evaluated outcome represents scattered distribution of the contour plot with significant loss of energy at the high frequency. Due to the frequency limitation of the speaker, the high pitch component is suppressed and reduced in the graph over the 20 kHz. The overall distribution of the sound level approximately corresponds to the theoretical graph since the color allocation can be described by the diagonal line, which is illustrated in the counterpart image as well. Moreover, the additional energy loss can be observed for the further movement toward the higher angle. Both of the figures confirm the relationship between barrier height and sound level by means of acoustic experiment in the anechoic chamber.


Binaural sound localizer for azimuthal movement detection based on diffraction.

Kim K, Choi A - Sensors (Basel) (2012)

(a) Theoretical spectral distribution of RDD structure. (b) Experimental spectral distribution of RDD structure.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472845&req=5

f8-sensors-12-10584: (a) Theoretical spectral distribution of RDD structure. (b) Experimental spectral distribution of RDD structure.
Mentions: The acoustically whitened signal based on the chamber transfer function is transmitted and recorded in five degree increments in order to generate the spectral distribution. From Equation (1), the theoretical spectral distribution for 360 degrees is illustrated in Figure 8(a), which denotes the significant level reduction at the elevated barrier height. It should be noted that the height of the barrier is proportional to the angle of the structure. In the vicinity of high angle, the spectrum is covered by low level values in particular for high frequency range. Also, the high level values become narrower for the low frequency range. The experimentally measured spectral distribution is exhibited in Figure 8(b) with 128 sample window length and ensemble averaged in order to reduce the variance of the signal. The spline interpolation with five times grid expansion in angle and frequency is used for Figure 8 in order to draw the smooth contours representing the comprehensive characteristics of the spectrum field. Unlike the theoretical result, the evaluated outcome represents scattered distribution of the contour plot with significant loss of energy at the high frequency. Due to the frequency limitation of the speaker, the high pitch component is suppressed and reduced in the graph over the 20 kHz. The overall distribution of the sound level approximately corresponds to the theoretical graph since the color allocation can be described by the diagonal line, which is illustrated in the counterpart image as well. Moreover, the additional energy loss can be observed for the further movement toward the higher angle. Both of the figures confirm the relationship between barrier height and sound level by means of acoustic experiment in the anechoic chamber.

Bottom Line: The gradient analysis of the ILD between the structured and unstructured microphone demonstrates the rotation directions as clockwise, counter clockwise, and no rotation of the sound source.Acoustic experiments with different types of sound source over a wide range of target movements show that the average true positive and false positive rates are 67% and 16%, respectively.Spectral analysis demonstrates that the low frequency delivers decreased true and false positive rates and the high frequency presents increases of both rates, overall.

View Article: PubMed Central - PubMed

Affiliation: Division of Electronics & Electrical Engineering, Dongguk University-Seoul, Seoul 100-715, Korea. kwkim@dongguk.edu

ABSTRACT
Sound localization can be realized by utilizing the physics of acoustics in various methods. This paper investigates a novel detection architecture for the azimuthal movement of sound source based on the interaural level difference (ILD) between two receivers. One of the microphones in the system is surrounded by barriers of various heights in order to cast the direction dependent diffraction of the incoming signal. The gradient analysis of the ILD between the structured and unstructured microphone demonstrates the rotation directions as clockwise, counter clockwise, and no rotation of the sound source. Acoustic experiments with different types of sound source over a wide range of target movements show that the average true positive and false positive rates are 67% and 16%, respectively. Spectral analysis demonstrates that the low frequency delivers decreased true and false positive rates and the high frequency presents increases of both rates, overall.

No MeSH data available.