Speaker device and filter coefficient generating device therefor

• US 9,118,997 B2
• Filed: 04/26/2010
• Issued: 08/25/2015
• Est. Priority Date: 04/26/2010
• Status: Active Grant

• Current Assignee: TOA Corporation
• Original Assignee: TOA Corporation
• Inventors: Miyata, Satoshi, Suetsugu, Toshimitsu
• Primary Examiner(s): Nguyen, Duc
• Assistant Examiner(s): Monikang, George
• Application Number:
  US13/642,859
• Publication Number:
  US 20130039512A1
• Time in Patent Office: 1,947 Days
• Field of Search: 381 17- 19, 381 97- 98
• US Class Current: 1/1
• CPC Class Codes: H04R 1/403 loud-speakers
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04R 3/12 for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407

Abstract

To provide a speaker device that can form a substantially uniform sound field over a range from a long distance to a short distance without significantly increasing a calculation load. A plurality of FIR filters 21 to 2n perform delay control of respective speakers so as to increase a delay time difference between adjacent speakers 51 to 5n in a line array speaker 5 toward one end of the line array speaker 5, and thereby over a wide range from a long distance to a short distance, a sound filed 12 is formed. Also, by adding a common shift delay time Dc to filter coefficients for the FIR filters 21 to 2n, the delay time difference between adjacent speakers 51 to 5n is made less than a sampling period of a sound signal to form a wide and uniform sound field 12.

Claims

1. A speaker device comprising:

a line array speaker that includes a plurality of speakers arranged on a same plane at predetermined intervals;

an IIR filter that is adapted to control an amplitude characteristic of a digital sound signal;

a plurality of FIR filters that correspond to said speakers and each delay common said digital sound signal input through said IIR filter; and

a plurality of D/A converters that each convert said delayed digital sound signal to an analog sound signal, wherein

said FIR filters delay said digital sound signal so as to increase a ratio of a delay time difference to the arrangement interval between adjacent speakers toward one end of said line array speaker; and

said FIR filters compensate for a phase characteristic of said IIR filter and delay said digital sound signal such that a minimum value among the delay time differences between the adjacent speakers becomes less than a sampling period of said digital sound signal, wherein

filter coefficients for said FIR filters are obtained by adding a common shift delay time for each of said FIR filters to values obtained by performing an inverse Fourier transform of frequency characteristics determined by turning said phase characteristic of said IIR filter upside down and rotating said phase characteristic of said IIR filter by a predetermined angle.

2. The speaker device according to claim 1, wherein

said FIR filters delay said digital sound signal so as to virtually array said speakers on a clothoid curve.

3. The speaker device according to claim 1, comprising

filter coefficient storage means adapted to rewritably hold filter coefficients for said FIR filters.

4. The speaker device according to claim 1, wherein

said shift delay time is an integral multiple of the unit delay time of said FIR filter.

5. A filter coefficient generating device for a speaker device that,

to a speaker device comprising:

a line array speaker that includes a plurality of speakers arranged on a same plane at predetermined intervals;

an IIR filter that is adapted to control an amplitude characteristic of a digital sound signal;

a plurality of FIR filters that correspond to said speakers and each delay common said digital sound signal;

a plurality of D/A converters that each convert said delayed digital sound signal to an analog sound signal; and

filter coefficient storage means adapted to rewritably hold filter coefficients for said FIR filters,

supplies the filter coefficients for said FIR filters, the filter coefficient generating device comprising;

frequency characteristics determination means adapted to, on a basis of user operation, determine frequency characteristics of each of said FIR filters;

filter coefficient calculation means adapted to perform an inverse Fourier transform of said frequency characteristics to obtain each of the filter coefficients for said FIR filters, and generates the filter coefficients for said FIR filters such that a minimum value among delay time differences between adjacent speakers becomes less than a sampling period of said digital sound signal; and

delay shift means adapted to add a common shift delay time to each of said filter coefficients, wherein

said frequency characteristics have phase characteristics to compensate for a phase characteristic of said IIR filter, wherein

said delay shift means adds said shift delay time to said filter coefficients obtained by performing said inverse Fourier transform of frequency characteristics determined by turning said phase characteristic of said IIR filter upside down and rotating said phase characteristic of said IIR filter by a predetermined angle.

6. A speaker device comprising:

a line array speaker that includes a plurality of speakers arranged on a same plane at predetermined intervals;

an IIR filter that is adapted to control an amplitude characteristic of a digital sound signal;

a plurality of FIR filters that correspond to said speakers and each delay common said digital sound signal input through said IIR filter; and

a plurality of D/A converters that each convert said delayed digital sound signal to an analog sound signal, wherein

said FIR filters delay said digital sound signal so as to increase a ratio of a delay time difference to the arrangement interval between adjacent speakers toward one end of said line array speaker; and

said FIR filters compensate for a phase characteristic of said IIR filter and delay said digital sound signal such that a minimum value among the delay time differences between the adjacent speakers becomes less than a sampling period of said digital sound signal, wherein

filter coefficients for said FIR filters are obtained by adding a common shift delay time for each of said FIR filters to values obtained by performing an inverse Fourier transform of frequency characteristics of said FIR filters; and

said shift delay time is approximately ½

of a tap length of said FIR filter.