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Sound source separation system, sound source separation method, and acoustic signal acquisition device

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Sound source separation system, sound source separation method, and acoustic signal acquisition device


A sound source separation system separates a target sound and a disturbance sound coming from an arbitrary direction other than the direction the target sound comes from. The system includes different-directional-signal-group generators and a sensitive region formation unit. The generators each generate two or more combinations of spectra of signals each of which has a different directivity, using received sound signals of microphones. The sensitive region formation unit determines, for each frequency band, whether or not a relationship between powers of the spectra in each combination simultaneously satisfies conditions each defined for each combination, using two or more combinations of the spectra of the signals generated by the respective different-directional-signal-group generators, and performs multidimensional band selection of assigning power of a spectrum selected beforehand to a spectrum of the target sound to be separated, for a frequency band where the conditions are simultaneously satisfied.

Browse recent Waseda University patents - Tokyo, JP
Inventors: Tetsunori KOBAYASHI, Kenzo AKAGIRI, Satoshi KANBA
USPTO Applicaton #: #20120308039 - Class: 381 92 (USPTO) - 12/06/12 - Class 381 
Electrical Audio Signal Processing Systems And Devices > Directive Circuits For Microphones

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The Patent Description & Claims data below is from USPTO Patent Application 20120308039, Sound source separation system, sound source separation method, and acoustic signal acquisition device.

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TECHNICAL FIELD

The present invention relates to a sound source separation system, a sound source separation method and an acoustic signal acquisition device which separate a target sound and a disturbance sound coming from an arbitrary direction other than a direction in which the target sound comes from, and is available for a case where a desired speech is acquired through a portable device like a cellular phone, and an in-vehicle device like a car navigation system.

BACKGROUND ART

In normal voice recognition, a speech uttered from a mouth is recorded through a close-talking type microphone, and is subjected to a recognition process. On the other hand, there are lots of applications, such as interaction with a robot, operation of an in-vehicle device like a car navigation system through a speech, and creation of conference minutes, where enforcing a user to use a close-talking type microphone is unnatural. In such applications, it is desirable that a speech should be recorded through a microphone provided at a system side and should be subjected to a recognition process. In a case where speech recording and voice recognition are performed through a microphone provided away from an utterer, however, an S/N ratio is deteriorated, it is difficult to hear, and the accuracy of voice recognition is extremely reduced.

In response to such problems, there is an attempt that a desired speech is selectively recorded by controlling the directivity using a microphone array. As such devices which control the directivity using a few microphones, there are an ultra directional microphone using two single-directional microphone units (see, patent literature 1) and a recording device for multi-channel stereo using four non-directional microphones (see, patent literature 2). Further, there is a microphone device having three pairs of microphones disposed around a base microphone (see, patent literature 3).

Moreover, there is proposed a scheme called SAFIA which separates a sound by utilizing a difference between sound pressures, reaching individual microphones and caused due to differences in positional relationships between the individual microphones and a sound source (see, patent literature 4). The scheme called SAFIA is a sound separation technique which causes output signals of a plurality of fixed microphones to undergo narrow-band spectrum analysis, and for a microphone that gives the largest power for each frequency band, performs band selection of assigning a sound of that frequency band to that microphone (see FIG. 8 to be discussed later). Patent Literature 1: Japanese Unexamined Patent Publication No. H10-126876 (claim 1, FIGS. 1 and 2, and abstract) Patent Literature 2: Japanese Unexamined Patent Publication No. 2002-223493 (claim 1, FIGS. 1 and 3, and abstract) Patent Literature 3: Japanese Unexamined Patent Publication No. 2002-271885 (claim 1, FIGS. 1 and 11, and abstract) Patent Literature 4: Japanese Patent Publication No. 3355598 (paragraphs 0006, 0007, FIG. 1 and abstract)

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

It is, however, difficult to sufficiently separate a desired speech from background noises by merely controlling the directivity through a microphone array, and to miniaturize the device. According to the ultra directional microphone disclosed in patent literature 1 and the recording device for multi-channel stereo disclosed in patent literature 2, controlling of the directivity is realized by a few microphones, miniaturization of the device may be possible, but a performance of separating a desired sound is not good enough. Further, the microphone device disclosed in patent literature 3 uses a total of seven microphones, so that it has the same problems as those of the microphone array.

According to the foregoing SAFIA disclosed in patent literature 4, band selection is performed by utilizing a difference between sound pressure levels of signals between microphones originating from positional relationships of a plurality of fixed microphones, but in performing band selection, unlike the present invention to be discussed later, directivity control appropriate for separation of a desired speech and noises is not performed, so that the separation performance thereof is not good enough. Note that only a separation process (see FIG. 8 to be discussed later) through band selection not including a generation process of a spectrum of a target subject to a separation process through band selection in the scheme called SAFIA will be hereinafter described as maximum level band selection (BS-MAX). According to the maximum level band selection (BS-MAX) performed in the SAFIA, powers of the same frequency band are compared for each frequency band between spectra subject to comparison, and band selection of assigning the largest power at individual frequency bands to a spectrum obtained by separation is performed, but according to the invention, in addition to performing such a maximum level band selection (BS-MAX), powers at the same frequency band are compared for each frequency band between spectra subject to comparison, and band selection of assigning the smallest powers at individual frequency bands to a spectrum obtained by separation is also performed, and this will be described as minimum level band selection (BS-MIN). Further, according to the present invention, not only it is determined whether or not one condition such as selecting the maximum or the minimum power is satisfied, but also it is determined whether or not a plurality of conditions are satisfied simultaneously, and this will be described as a multidimensional band selection (BS-multiD), and the case of two conditions will be described as a two-dimensional band selection (BS-2D), and the case of three conditions will be described as a three-dimensional band selection (BS-3D).

It is an object of the invention to provide a sound source separation system, a sound source separation method and an acoustic signal acquisition device which can accurately separate a target sound and a disturbance sound coming from an arbitrary direction, and enables miniaturization of a device.

Means for Solving the Problems

<<Invention of a Sound Source Separation System>>

<Two Microphones Type Invention> Invention of a Type that Two Microphones Are Used

According to the invention, a sound source separation system that separates a target sound and a disturbance sound coming from an arbitrary direction other than a direction in which the target sound comes from and comprises: two microphones disposed in such a manner as to be spaced away from each other; a target sound superior signal generator which performs a linear combination process for emphasizing the target sound using received sound signals of the two microphones on a time domain or a frequency domain to generate at least one target sound superior signal; a target sound inferior signal generator which performs a linear combination process for suppressing the target sound using the received sound signals of the two microphones on a time domain or a frequency domain to generate at least one target sound inferior signal to be paired with the target sound superior signal; and a separator which separates the target sound and the disturbance sound from each other using a spectrum of the target sound superior signal generated by the target sound superior signal generator or obtained by a subsequent frequency analysis and a spectrum of the target sound inferior signal generated by the target sound inferior signal generator or obtained by a subsequent frequency analysis.

“A sound source separation system that separates a target sound and a disturbance sound coming from an arbitrary direction other than a direction in which the target sound comes from” means a system that can perform sound source separation in a case where a direction in which the disturbance sound comes from is not specified, other than a case where both directions in which the target sound and the disturbance sound come from are already known, like a case where sound source separation is performed through independent component analysis (ICA). Moreover, “a disturbance sound coming from an arbitrary direction other than a direction in which the target sound comes from” does not always mean all directions in 360 degrees other than the direction in which the target sound comes from, but may be an arbitrary direction in a range other than the direction in which the target sound comes from and the adjacent directions, and for example, when θ=0 degree is the direction in which the target sound comes from, only a range of θ=−90 to 90 degrees may be a separation target range, and in short, the disturbance sound comes from an unspecified direction. The same is true on other inventions.

“Performing a linear combination process for emphasizing the target sound using received sound signals of the two microphones on a time domain or a frequency domain” and “performing a linear combination process for suppressing the target sound using the received sound signals of the two microphones on a time domain or a frequency domain” include (1) performing linear combination processes for emphasizing and suppressing the target sound using the received sound signals of the two microphones as signals on a time domain, and generating a target sound superior signal and a target sound inferior signal as signals on a time domain, and (2) performing frequency analysis on the received sound signals (signals on a time domain) of the two microphones to make signals on a frequency domain (spectra), performing linear combination processes for emphasizing and suppressing the target sound, and generating a target sound superior signal and a target sound inferior signal as signals (spectra) on a frequency domain. The same is true on other inventions.

Further, when the target sound superior signal generated by the target sound superior signal generator is a signal on a frequency domain, “a spectrum of the target sound superior signal generated by the target sound superior signal generator or obtained by a subsequent frequency analysis” is that signal itself and is a signal on a frequency domain obtained by frequency analysis of that signal when the target sound superior signal obtained by the target sound superior signal generator is a signal on a frequency domain. The same is true on “a spectrum of the target sound inferior signal generated by the target sound inferior signal generator or obtained by a subsequent frequency analysis”. The same is true on other inventions.

The “linear combination process” includes a process of acquiring a sum or a difference, and a process of multiplying a coefficient. The same is true on other inventions.

“Separating the target sound and the disturbance sound” using “the spectrum of the target sound superior signal” and “the spectrum of the target sound inferior signal” includes, for example, a process for each frequency band, i.e., a process of using both powers of the spectrum of the target sound superior signal and the spectrum of the target sound inferior signal at the same frequency band. The same is true on other inventions. The same process can be performed when amplitude values at the same frequency band are used, so that a process using powers represents both processes in the specification.

“The target sound” and “the disturbance sound” are mainly speeches of a human, but include, for example, a music, an animal call, natural sounds, such as a thunder, a ripping wave, and a murmur, various sound effects, such as a buzzer, an alarm sound, a honker, and an alarm whistle, and various mechanical sounds, such as a sound from a road, running sound of a vehicle, a takeoff sound of an airplane, and an operational sound of a machine. The same is true on other inventions.



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Sound source localization apparatus and method
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stats Patent Info
Application #
US 20120308039 A1
Publish Date
12/06/2012
Document #
13486798
File Date
06/01/2012
USPTO Class
381 92
Other USPTO Classes
International Class
04R3/00
Drawings
50



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