SOUND COLLECTION/REPRODUCTION METHOD AND DEVICE

• US 20100027808A1
• Filed: 11/20/2006
• Published: 02/04/2010
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: Hareo Hamada
• Original Assignee: Dimagic Corporation
• Inventors: Hamada, Hareo, Goto, Akira, Murayama, Yoshitaka
• Granted Patent: US 8,116,479 B2
• Time in Patent Office: Days
• US Class Current: 381/92
• CPC Class Codes: H04R 5/027 Spatial or constructional arrangements of microphones, e.g. in dummy heads
• CPC Class Codes: H04S 2400/15 Aspects of sound capture and related signal processing for recording or reproduction
• CPC Class Codes: H04S 3/002 Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution control circuits for electronic adaptation of the sound field H04S7/30
• CPC Class Codes: H04S 5/005 of the pseudo five- or more-channel type, e.g. virtual surround

Abstract

To provide a sound collection system using a plurality of microphones arranged in the proximity to one another and having an excellent directivity for an arbitrary position in the sound field space. A plurality of control points are set around a plurality of sound collecting microphones. A desired response function matrix A(ω) and a transfer function matrix C(ω) between the control points and the respective microphones are measured. A control filter H arranged in a digital signal processing unit (2) is connected to each of the microphones constituting the sound collection device (1). The control filters H are arranged for the number of output channels of a reproduction unit (4). An output of each of the control filters H is added for each channel and outputted to each channel of the reproduction unit (4). By specifying a microphone directivity upon sound collection at a control point, the control filters H are decided according to the measured desired response function matrix A(ω) and the transfer function matrix C(ω) of the specified control point.

Claims

1. A sound collection/reproduction method according to which a plurality of sound collection devices are arranged in proximity to one another, control filters in a number corresponding to the number of reproduction channels are connected to each of the sound collection devices, and the output signals from the control filters of each of the channels are added for each of the channels and output from each of the reproduction channels, wherein

the control filters are obtained by setting a plurality of control points in a sound field around the plurality of sound collection devices arranged in proximity to one another, determining a desired response function matrix and a transfer function matrix between the control points and each of the sound collection devices on the basis of measurement values, and, in cases where the directivity of the sound collection devices is designated, determining values of the control filters on the basis of the desired response function matrix and transfer function matrix between the control points corresponding to the designated directivity and each of the sound collection devices.

2. The sound collection/reproduction method according to claim 1, wherein the control filter is represented by H(ω

)=[C(ω

)^T·

C(ω

)]<sup>−

1</sup>C(ω

)^T·

A(ω

), where the control filter matrix is H(ω

), the desired response function matrix is A(ω

), and the transfer function is C(ω

), and is obtained by solving the inverse matrix [C(ω

)^T·

C(ω

)]<sup>−

1</sup>C(ω

)^T of the transfer function matrix C(ω

).

3. The sound collection/reproduction method according to claim 1, wherein only the signal of the channel for which monitoring is performed is designated and extracted from among the signals of each of the channels from an adder of each of the channels, and the extracted channel signal is output to a two-channel sound collection device via a virtual sound source reproduction processing unit.

4. The sound collection/reproduction method according to claim 3, wherein the virtual sound source reproduction processing unit divides the signals of each of the channels for use as left and right output signals of the reproduction device, and outputs the divided left and right signals of each of the channels to left and right reproduction devices via the control filters conforming to the characteristic of the reproduction device.

9. The sound collection/reproduction method according to claim 2, wherein only the signal of the channel for which monitoring is performed is designated and extracted from among the signals of each of the channels from an adder of each of the channels, and the extracted channel signal is output to a two-channel sound collection device via a virtual sound source reproduction processing unit.

5. A sound collection/reproduction device comprising:

a plurality of sound collection devices arranged in proximity to one another;

a digital signal processing unit which processes sounds collected by each of the sound collection devices; and

a reproduction output unit which outputs a speech signal which is output by the digital signal processing unit, wherein

the reproduction output unit is provided with reproduction devices of one or a plurality of channels,

the digital signal processing unit is provided with control filters in a number corresponding to the number of reproduction channels connected to each of the plurality of sound collection devices, and adders in a number corresponding to the number of channels, which add the outputs of the control filters of each of the reproduction channels connected to each of the sound collection devices for each channel, the outputs of the adder of each of the channels being connected to the reproduction device of each of the channels of the reproduction processing unit,

the control filters are obtained by setting a plurality of control points in a sound field around the plurality of sound collection devices arranged in proximity to one another, determining a desired response function matrix and a transfer function matrix between the control points and each of the sound collection devices on the basis of measurement values, and, in cases where the directivity of the sound collection devices is designated, determining values of the control filters on the basis of the desired response function matrix and transfer function matrix between the control points corresponding to the designated directivity and each of the sound collection device, and

the digital signal processing unit is provided with a directivity control unit to which directivity control data are input in order to determine the directivity during sound collection by controlling the control filters.

6. The sound collection/reproduction device according to claim 5, wherein the control filter is represented by H(ω

)=[C(ω

)^T·

C(ω

)]<sup>−

1</sup>C(ω

)^T·

A(ω

), where the control filter matrix is H(ω

), the desired response function matrix is A(ω

), and the transfer function is C(ω

), and is obtained by solving the inverse matrix [C(ω

)^T·

C(ω

)]<sup>−

1</sup>C(ω

)^T of the transfer function matrix C(ω

).

7. The sound collection/reproduction device according to claim 5, wherein

a monitoring processing unit is connected to the digital signal processing unit,

the monitoring processing unit being provided with a virtual sound source reproduction processing unit which converts the signal from the adder of each of the channels provided in the digital signal processing unit into an output signal of a two-channel monitoring device.

8. The sound collection/reproduction device according to claim 7, wherein the virtual sound source reproduction processing unit comprises:

a control filter which divides the outputs from the adder of each of the channels provided in the digital signal processing unit into two to match two left and right channels of the monitoring device, and sets a filter coefficient corresponding to the monitoring device for each of the two divided left and right signals of each of the channels;

left and right adders which add the outputs from the control filters of each of the channels; and

an output unit which outputs signals from the left and right adders to each of the channels of the monitoring device.

10. The sound collection/reproduction device according to claim 6, wherein

a monitoring processing unit is connected to the digital signal processing unit,

the monitoring processing unit being provided with a virtual sound source reproduction processing unit which converts the signal from the adder of each of the channels provided in the digital signal processing unit into an output signal of a two-channel monitoring device.