Sound processing apparatus, method for correcting phase difference, and computer readable storage medium

1. A sound processing apparatus for processing received sounds comprising:

a plurality of sound receiving units, each of the sound receiving units outputting a sound signal corresponding to a received sound;

a converting unit for converting the sound signals in a time domain into converted signals in a frequency domain;

a calculating unit for obtaining a power spectral ratio between two converted signals;

a deriving unit for deriving a phase correction value by using the power spectral ratio, the phase correction value being derived on the basis of one of the two converted signals; and

a correcting unit for correcting a phase of the other of the two converted signals to a phase of the one of the two converted signals to calibrate sensitivity of at least one of the plurality of sound receiving units.

2. The sound processing apparatus according to claim 1 , wherein the calculating unit obtains a ratio of power spectrum between the two converted signals.

3. The sound processing apparatus according to claim 2 , wherein the phase correction value is expressed in the form of an equation:

P comp (ω)=α F{S 2 (ω)/ S 1 (ω)}+β

in which ω is an angular frequency, Pcomp(ω) is the phase correction value, S 1 (ω) is a power spectrum of the one of the two converted signals, S 2 (ω) is a power spectrum of the other of the two converted signals, α and β are constants, and F{S 2 (ω)/S 1 (ω)} is a function of S 2 (ω)/S 1 (ω).

4. The sound processing apparatus according to claim 2 , wherein the phase correction value is expressed in the form of an equation:

P comp(ω)=[α F{S 1 (ω)/ S 2 (ω)}]ω+β

in which ω is an angular frequency, Pcomp(ω) is the phase correction value, S 1 (ω) is a power spectrum of the one of the two converted signals, S 2 (ω) is a power spectrum of the other of the two converted signals, α and β are constants, and F{S 1 (ω)/S 2 (ω)} is a function of S 1 (ω)/S 2 (ω).

5. The sound processing apparatus according to claim 3 , wherein the function is a logarithm function and the correcting unit executes an addition of the phase correction value to the phase of the other of the two converted signals.

6. The sound processing apparatus according to claim 4 , wherein the function is a logarithm function and the correcting unit executes an addition of the phase correction value to the phase of the other of the two converted signals.

7. The sound processing apparatus according to claim 1 , wherein the calculating unit is capable of obtaining a ratio between amplitude spectrum of the two converted signal.

8. The sound processing apparatus according claim 1 , further comprising;

a smoothing unit for smoothing a temporal variation of the phase correction value, wherein the correcting unit corrects the phase of the sound signal on the basis of the phase correction value smoothed by the smoothing unit.

9. A method for correcting a phase difference between received sound signals, the method comprising the operations of:

transforming each of sound signals in a time domain into a converted signal in a frequency domain respectively, each of the sound signals being corresponding to respective received sound signals;

executing a calculation for obtaining a power spectral ratio between two of the converted signals;

deriving a phase correction value by using the power spectral ratio, the phase correction value being derived on the basis of one of the two of the converted signals; and

correcting a phase of the other of the two of the converted signals to a phase of the one of the two converted signals to calibrate a sensitivity for receiving at least one of the received sound signals.

10. A storage medium storing a computer-readable program for causing a computer to execute a method for correcting a phase difference between received sound signals, the method comprising the operations of:

transforming each of sound signals into a converted signal in a frequency domain respectively, each of the sound signals being corresponding to respective received sound signals;

executing a calculation for obtaining a power spectral ratio between two of the converted signals;

deriving a phase correction value by using the power spectral ratio, the phase correction value being derived on the basis of one of the two of the converted signals; and

correcting a phase of the other of the two of the converted signals to a phase of another of the two converted signals to calibrate a sensitivity for receiving at least one of the received sound signals.