Collecting sound device with directionality, collecting sound method with directionality and memory product

• US 20070274536A1
• Filed: 09/13/2006
• Published: 11/29/2007
• Est. Priority Date: 05/26/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Matsuo, Naoshi
• Granted Patent: US 8,036,888 B2
• Time in Patent Office: Days
• US Class Current: 381/94.300
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2430/20 Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic H04R2203/12 takes precedence
• CPC Class Codes: H04R 3/04 for correcting frequency response

Abstract

A sound input from sound sources existing in a plurality of directions is accepted and converted into a signal on a frequency axis. A suppressing function to suppress the converted signal on a frequency axis is computed, an amplitude component of a signal on a frequency axis is multiplied by the computed suppressing function and the converted signal on a frequency axis is corrected. A phase component of each converted signal on a frequency axis is computed for each frequency and a difference of phase components is computed. A probability value indicative of probability of existence of a sound source in a predetermined direction is specified based on the computed difference and a suppressing function to suppress a sound input from a sound source other than a sound source in a predetermined direction is computed based on the specified probability value.

Claims

1. A collecting sound device with directionality comprising:

a plurality of voice accepting means for accepting a sound input from sound sources existing in a plurality of directions and converting the sound input into a signal on a time axis;

signal converting means for converting each signal on a time axis into a signal on a frequency axis;

phase component computing means for computing a phase component of each signal on a frequency axis converted by the signal converting means for each frequency;

phase difference computing means for computing a difference of phase components between signals on a frequency axis computed by the phase component computing means;

probability value specifying means for specifying a probability value indicative of probability of existence of a sound source in a predetermined direction based on the difference of phase components computed by the phase difference computing means;

suppressing function computing means for computing a suppressing function to suppress a sound input from a sound source other than a sound source in a predetermined direction based on the probability value specified by the probability value specifying means;

signal correcting means for multiplying an amplitude component of a signal on a frequency axis by the computed suppressing function and correcting the converted signal on a frequency axis; and

signal restoring means for restoring the corrected signal on a frequency axis to a signal on a time axis.

2. The collecting sound device with directionality according to claim 1, further comprising

means for determining whether the difference of phase components computed by the phase difference computing means is within a predetermined range or not, wherein

the suppressing function is set to 1 in a phase width for which it is determined that the difference of phase components is within a predetermined range.

3. The collecting sound device with directionality according to claim 2, further comprising

means for computing a separation phase width corresponding to a range of a phase component, for which a sound input from a sound source other than a sound source in a predetermined direction needs to be suppressed, based on the probability value specified by the probability value specifying means, wherein

the suppressing function is set to 1 in the phase width and set as a positive real number which gradually decreases with distance from the phase width and becomes 0 in a range beyond the computed separation phase width.

4. A collecting sound device with directionality comprising a processor capable of performing the steps of

accepting a sound input from sound sources existing in a plurality of directions;

converting the sound input into a signal on a time axis;

converting each signal on a time axis into a signal on a frequency axis;

computing a phase component of each converted signal on a frequency axis for each frequency;

computing a difference of computed phase components between signals on a frequency axis;

specifying a probability value indicative of probability of existence of a sound source in a predetermined direction based on the computed difference of phase components;

computing a suppressing function to suppress a sound input from a sound source other than a sound source in a predetermined direction based on the specified probability value;

multiplying an amplitude component of a signal on a frequency axis by the computed suppressing function and correcting the converted signal on a frequency axis; and

restoring the corrected signal on a frequency axis to a signal on a time axis.

5. The collecting sound device with directionality according to claim 4, the processor being further capable of performing the steps of:

determining whether the computed difference of phase components is within a predetermined range or not; and

setting the suppressing function to 1 in a phase width for which it is determined that the difference of phase components is within a predetermined range.

6. The collecting sound device with directionality according to claim 5, the processor being further capable of performing the steps of:

computing a separation phase width corresponding to a range of a phase component, for which a sound input from a sound source other than a sound source in a predetermined direction needs to be suppressed, based on the specified probability value; and

setting the suppressing function to 1 in the phase width and setting the suppressing function as a positive real number which gradually decreases with distance from the phase width and becomes 0 in a range beyond the computed separation phase width.

7. A collecting sound method with directionality comprising the steps of

accepting a sound input from sound sources existing in a plurality of directions;

converting the sound input into a signal on a time axis;

converting each signal on a time axis into a signal on a frequency axis;

computing a phase component of each converted signal on a frequency axis for each frequency;

computing a difference of computed phase components between signals on a frequency axis;

specifying a probability value indicative of probability of existence of a sound source in a predetermined direction based on the computed difference of phase components;

computing a suppressing function to suppress a sound input from a sound source other than a sound source in a predetermined direction based on the specified probability value;

multiplying an amplitude component of a signal on a frequency axis by the computed suppressing function and correcting the converted signal on a frequency axis; and

restoring the corrected signal on a frequency axis to a signal on a time axis.

8. The collecting sound method with directionality according to claim 7, further comprising the steps of

determining whether the computed difference of phase components is within a predetermined range or not;

and

setting the suppressing function to 1 in a phase width for which it is determined that the difference of phase components is within a predetermined range.

9. The collecting sound method with directionality according to claim 8, further comprising the steps of

computing a separation phase width corresponding to a range of a phase component, for which a sound input from a sound source other than a sound source in a predetermined direction needs to be suppressed, based on the specified probability value;

and

setting the suppressing function to 1 in the phase width and setting the suppressing function as a positive real number which gradually decreases with distance from the phase width and becomes 0 in a range beyond the computed separation phase width.

10. A memory product storing a computer program, wherein the computer program comprises the steps of

causing a computer to accept a sound input from sound sources existing in a plurality of directions;

causing a computer to convert the sound input into a signal on a time axis;

causing a computer to convert each signal on a time axis into a signal on a frequency axis;

causing a computer to compute a phase component of each converted signal on a frequency axis for each frequency;

causing a computer to compute a difference of computed phase components between signals on a frequency axis;

causing a computer to specify a probability value indicative of probability of existence of a sound source in a predetermined direction based on the computed difference of phase components;

causing a computer to compute a suppressing function to suppress a sound input from a sound source other than a sound source in a predetermined direction based on the specified probability value;

causing a computer to multiply an amplitude component of a signal on a frequency axis by the computed suppressing function and correct the converted signal on a frequency axis;

causing a computer to restore the corrected signal on a frequency axis to a signal on a time axis; and

causing a computer to suppress a sound input from a sound source other than a sound source in a predetermined direction.

11. The memory product storing a computer program according to claim 10, wherein the computer program further comprises the steps of

causing a computer to determine whether the computed difference of phase components is within a predetermined range or not;

and

causing a computer to set the suppressing function to 1 in a phase width for which it is determined that the difference of phase components is within a predetermined range.

12. The memory product storing a computer program according to claim 11, wherein the computer program further comprises the steps of

causing a computer to compute a separation phase width corresponding to a range of a phase component, for which a sound input from a sound source other than a sound source in a predetermined direction needs to be suppressed, based on the specified probability value;

and

causing a computer to set the suppressing function to 1 in the phase width and set the suppressing function as a positive real number which gradually decreases with distance from the phase width and becomes 0 in a range beyond the computed separation phase width.