Sound field control apparatus and sound field control method
View Patent ↗A sound field control apparatus appropriately presenting desired sound in a listening area and sufficiently reducing the sound in a nearby area without constraint on configuration arrangement includes: a listening compensation filter processing a signal from a sound source using a control characteristic and outputting the signal to a second speaker; and a control filter processing the signal from the listening compensation filter using a control characteristic and outputting the signal to a first speaker. The characteristic of the control filter is a first previously-set characteristic whereby reproduced sound from the second speaker is reduced by reproduced sound from the first speaker at a first control position. The characteristic of the listening compensation filter is a second previously-set characteristic whereby sound having a predetermined target acoustic characteristic is presented by reproduced sounds from the first and second speakers at a second control position.
1. A sound field control apparatus comprising:
a listening compensation filter which generates a second output signal by performing signal processing on an input signal from a sound source according to a control characteristic that is previously set, and outputs the second output signal to a second speaker; and
a control filter which generates a first output signal by performing signal processing on the second output signal from the listening compensation filter according to a control characteristic that is previously set, and outputs the first output signal to a first speaker,
wherein the control characteristic of the control filter is previously set as a first control characteristic that allows a reproduced sound from the second speaker to be reduced at a first control position by a reproduced sound from the first speaker, and
the control characteristic of the listening compensation filter is previously set as a second control characteristic that allows a sound having a predetermined target acoustic characteristic to be presented at a second control position by the reproduced sounds from the first and second speakers.
2. The sound field control apparatus according to claim 1 ,
wherein, by performing:
generating a target characteristic signal by performing signal processing on the input signal from the sound source according to the predetermined target acoustic characteristic;
generating a second detection signal by detecting the reproduced sounds from the first and second speakers using a microphone located at the second control position; and
updating the control characteristic of the listening compensation filter according to the input signal, the target characteristic signal, and the second detection signal,
the updated control characteristic is calculated and set as the second control characteristic.
3. The sound field control apparatus according to claim 2 ,
wherein, in the updating, a difference between the target characteristic signal and the second detection signal is calculated and the control characteristic of the listening compensation filter is updated using the input signal to reduce the difference.
4. The sound field control apparatus according to claim 1 ,
wherein the first control characteristic of the control filter is calculated and set before the second control characteristic is set.
5. The sound field control apparatus according to claim 1 ,
wherein, by performing:
generating a first detection signal by detecting the reproduced sounds from the first and second speakers using a microphone located at the first control position; and
updating the control characteristic of the control filter according to the second output signal from the listening compensation filter and the first detection signal,
the updated control characteristic is calculated and set as the first control characteristic.
6. The sound field control apparatus according to claim 1 , comprising
an n number of the control filters, n being an integer that is at least 2,
wherein the listening compensation filter outputs the second output signal to an n number of the second speakers, and
each of the n control filters performs signal processing on the second output signal to be outputted to one of the n second speakers that corresponds to the control filter.
7. The sound field control apparatus according to claim 6 , further comprising
an adder which adds the first output signals outputted from the n control filters and outputs an addition signal,
wherein the first speaker outputs the reproduced sound according to the addition signal outputted from the adder.
8. The sound field control apparatus according to claim 1 , comprising:
a first listening compensation filter and a first control filter which are the listening compensation filter and the control filter, respectively; and
a second listening compensation filter and a second control filter,
wherein the second listening compensation filter generates a third output signal by performing, according to a control characteristic that is previously set, signal processing on a current acoustic signal to be processed, and outputs the third output signal to a third speaker,
the second control filter generates a fourth output signal by performing signal processing on the third output signal from the second listening compensation filter according to a control characteristic that is previously set, and outputs the fourth output signal to the first speaker,
the control characteristic of the second control filter is previously set as a third control characteristic that allows a reproduced sound from the third speaker to be reduced at the second control position by the reproduced sound from the first speaker, and
the control characteristic of the second listening compensation filter is previously set as a fourth control characteristic that allows a sound having a predetermined target acoustic characteristic to be presented at the first control position by the reproduced sounds from the first and third speakers.
9. The sound field control apparatus according to claim 8 ,
wherein the second listening compensation filter performs signal processing on the input signal, as the acoustic signal, which is from the sound source and on which signal processing is performed by the first listening compensation filter.
10. The sound field control apparatus according to claim 8 ,
wherein the second listening compensation filter performs signal processing on a signal as the acoustic signal, the signal being different from the input signal which is outputted from the sound source and on which signal processing is performed by the first listening compensation filter.
11. The sound field control apparatus according to claim 8 ,
wherein the third output signal from the second listening compensation filter is added to the second output signal from the first listening compensation filter by an adder, and a resulting signal is outputted to the second speaker instead of the third speaker.
12. The sound field control apparatus according to claim 1 ,
wherein each of the listening compensation filter and the control filter includes a plurality of taps and performs filtering using previous data included in a current signal to be processed.
13. A sound field control method comprising:
generating a second output signal by performing signal processing on an input signal from a sound source according to a second control characteristic, and outputting the second output signal to a second speaker; and
generating a first output signal by performing signal processing on the second output signal from a listening compensation filter according to a first control characteristic, and outputting the first output signal to a first speaker,
wherein the first control characteristic allows a reproduced sound from the second speaker to be reduced at a first control position by a reproduced sound from the first speaker, and
the second control characteristic allows a sound having a predetermined target acoustic characteristic to be presented at a second control position by the reproduced sounds from the first and second speakers.