JPH10201000A - FIR filter, headphone device and speaker device using the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To significantly reduce the number of required delay devices, to reduce the circuit scale and cost. A signal processing circuit of an out-of-head sound image localization type headphone device. For the audio signal Sa corresponding to the sound source,
The FIR filter unit 20L convolves the impulse response obtained by converting the transfer function _HL from the sound source to the left ear of the listener to the time axis to form a left audio signal Sbl.
At 0R, a right sound signal Sbr is formed by convolving an impulse response obtained by converting a transfer function H _R from the sound source to the right ear of the listener to the time axis. When the headphones are driven by the audio signals Sbl and Sbr, the sound image based on the audio signal Sa is localized at the position of the sound source. The delay units 22 constituting the delay lines of the filter units 20L and 20R are commonly used, and the number of required delay units 22 is greatly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an FIR filter having a plurality of FIR filters, a headphone device and a speaker device using the same. More specifically, by sharing a part or all of the delay units that constitute the delay lines of a plurality of FIR filter units, the number of required delay units can be significantly reduced, and the circuit scale and cost can be reduced. The present invention relates to an FIR filter or the like.

[0002]

2. Description of the Related Art Conventionally, an out-of-head sound image localization type headphone device in which a sound image based on an input audio signal is localized outside a head has been proposed. FIG. 9 shows the configuration of an out-of-head sound image localization type headphone device 200.

First, the principle of the headphone device 200 will be described with reference to FIG. The sound is transmitted from the sound source S to the left ear and the right ear of the listener M through paths having transfer functions of H _L and H _R , respectively. Therefore, in order to reproduce this state using the headphones, with obtaining an output audio signal Sbl input audio signal Sa corresponding to the sound source S through a filter for implementing the transfer function H _L, the input audio signal S
generate an output right audio signal Sbr through a filter for implementing the transfer function H _R of a, these audio signals Sbl, may be driven headphones by Sbr.

Next, the configuration of the headphone device 200 shown in FIG. 9 will be described. The headphone device 200 includes an input terminal 201 to which an input audio signal Sa is supplied, and an input audio signal Sa.
A / D (analog-to-digita) that converts
l) It has a converter 202 and signal processing circuits 203L and 203R for performing a filtering process on the input audio signal Sa converted into a digital signal.

The signal processing circuit 203L has a configuration of an FIR (finite impulse response) filter as shown in FIG. That is, the signal processing circuit 203L includes an input terminal 211 to which an input audio signal Sa is supplied and a plurality of delay units 212 connected in series.
And a plurality of multipliers 21 for multiplying a signal of each tap of the delay line by a coefficient.
3, an adder 214 for adding the output signal of the multiplier 213 to obtain an output left audio signal Sbl, and an output terminal 215 for deriving the output left audio signal Sbl. The delay unit 212 delays the audio signal Sa by a unit time (one sampling interval).

Here, in the plurality of multipliers 213, the impulse response at each time when the transfer function H _L is converted to the time axis is used as a coefficient. As a result, in the signal processing circuit 203L, the output left audio signal Sbl is formed by convolving the input audio signal Sa with the impulse response obtained by converting the transfer function _HL to the time axis. Note that the impulse response is calculated in advance by measurement or calculation.

Although detailed description is omitted, the signal processing circuit 20
3R is configured similarly to the signal processing circuit 203L described above. Then, the signal processing circuit 203R, the input audio signal Sa transfer function H _R a convolved conversion impulse response in the time axis with respect to the output right audio signal Sbr is formed.

Returning to FIG. 9, the headphone device 20
0 is a D / A (digital-to-analog) converter 204L, 2 which converts the audio signals Sbl, Sbr output from the signal processing circuits 203L, 203R into analog signals, respectively.
04R and the audio signals Sbl and S converted to analog signals
It has amplifiers 205L and 205R for amplifying br, respectively, and headphones 206 to which amplified audio signals Sbl and Sbr are respectively supplied.

The operation of the headphone device 200 shown in FIG. 9 will be described. Input audio signal S supplied to input terminal 201
a is supplied to the signal processing circuits 203L and 203R after being converted into a digital signal by the A / D converter 202. Signal processing circuit 203L, 203R in the transfer function H _L for the input audio signal Sa, respectively, H _R impulse response generated by converting a time axis is convolved output audio signal S
bl and the output right audio signal Sbr are formed.

[0010] The audio signals Sbl and Sbr are converted into analog signals by D / A converters 204L and 204R, respectively, and then supplied to headphones 206 after being amplified by amplifiers 205L and 205R. Therefore, the headphones 206 are driven by the audio signals Sbl and Sbr,
The sound image by the input audio signal Sa can be localized outside the head. That is, when the listener M wears the headphones 206, a state in which the sound source S is outside the head as shown in FIG. 10 is reproduced.

[0011]

The headphone device 200 shown in FIG. 9 has the signal processing circuits 203L and 203R having the FIR filter configuration, and requires many delay units 212. Therefore, delay device 2
If the digital signal processing IC 12 is to be constituted by a data RAM (random access memory) incorporated in the digital signal processing IC, the scale of the digital signal processing IC increases and the cost increases. This is the data RAM
This is because the ratio of the digital signal processing IC to the scale and cost is large.

In view of the above, the present invention is intended to greatly reduce the number of required delay units, thereby reducing the circuit scale and cost.

[0013]

SUMMARY OF THE INVENTION An FIR filter according to the present invention has a plurality of FIR filter units, each of which includes a delay line composed of a plurality of delay units connected in series. A plurality of multipliers for multiplying the signal of each tap of the delay line by a coefficient, respectively, and an adder for adding the output signals of the plurality of multipliers, and constituting a delay line of a plurality of filter units Some or all of them are common.

In the present invention, a plurality of FIR filter sections perform a filtering process on the same input signal to form a plurality of output signals. In this case, multiple FIRs
Since delay processing is performed on the same input signal in the delay lines of the filter units, a part or all of the delay units constituting the delay lines of the plurality of filter units are common. For example, when two FIR filter units are provided and all the delay units are common, the number of required delay units is 1/1 of that when two FIR filter units are separately configured.
It becomes 2.

[0015] Further, the headphone device according to the present invention comprises:
A first and a second FIR filter section for reproducing two systems of impulse responses from a sound source previously measured or calculated to a left ear and a right ear of a listener; A signal processing means for convolving the two impulse responses with respect to the input audio signal to obtain an output left audio signal and an output right audio signal, and driving the headphones with the output left audio signal and the output right audio signal. In the headphone device in which the sound image based on the input audio signal is localized outside the head, part or all of the delay units constituting the delay lines of the first and second FIR filter units are shared.

In the present invention, the first and second FIs
In the R filter section, the same input audio signal is subjected to a filtering process to form an output left audio signal and an output right audio signal. In this case, since the same input audio signal is subjected to delay processing in the delay lines of the first and second FIR filter units, the delay lines of the delay lines forming the delay lines of the first and second FIR filter units Some or all are common. For example, when all the delay units are common, the number of required delay units is １ ／ of that when two FIR filter units are separately configured.

Also, the speaker device according to the present invention has a plurality of FIR filter sections, and the plurality of FIR filter sections convolve a plurality of impulse responses with respect to an input audio signal to output a plurality of output audio signals. A signal processing means for obtaining a signal, wherein a plurality of speakers are driven by output audio signals of a plurality of systems so that a sound image based on the input audio signal is localized at an arbitrary position. A part or all of the delay units constituting the delay line are made common.

In the present invention, a plurality of FIR filter units perform a filtering process on the same input audio signal to form a plurality of output audio signals. In this case, since a delay process is performed on the same input audio signal in the delay lines of the plurality of FIR filter units, a part or all of the delay units constituting the delay lines of the plurality of FIR filter units are shared. You. For example, when two FIR filter units are provided and all delay units are common, the number of required delay units is １ ／ of that when two FIR filter units are separately configured. Become.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of an out-of-head sound image localization type headphone device 10 as a first embodiment. This headphone device 10 is similar to the above-described headphone device 200 (see FIG. 9).
Are reproduced using headphones.

The headphone device 10 receives an input audio signal Sa
, An A / D converter 12 for converting the input audio signal Sa into a digital signal, and a signal processing circuit 13 for performing a filtering process on the input audio signal Sa converted into the digital signal. doing.

The signal processing circuit 13 is configured as shown in FIG. That is, the signal processing circuit 13 includes an input terminal 21 to which the input audio signal Sa is supplied, and a plurality of delay units 22.
Are connected in series, a delay line with taps for delaying the input audio signal Sa, a plurality of multipliers 23 for multiplying a signal of each tap of the delay line by a coefficient, and a plurality of multipliers 23 output signals and output left audio signal S
and a plurality of adders 24 for obtaining the audio signal Sbl.
, A plurality of multipliers 26 for multiplying the signal of each tap of the delay line by a coefficient, and a plurality of outputs for adding the output signals of the plurality of multipliers 26 to obtain an output left audio signal Sbr. And an output terminal 28 for deriving the audio signal Sbr. The delay unit 22 outputs the audio signal S
a is given a delay of a unit time (one sampling interval).

Here, an FIR filter unit 20L is constituted by a delay line composed of a plurality of delay units 22, a plurality of multipliers 23 and a plurality of adders 24, while a delay line composed of a plurality of delay units 22 and a plurality of multiplication units The FIR filter unit 20R includes the adder 26 and the plurality of adders 27. In the plurality of multipliers 23, an impulse response at each time when the transfer function _HL is converted into a time axis is used as a coefficient. Thereby, the FIR filter unit 20
At L, an input left audio signal Sbl is formed by convolving the input audio signal Sa with the impulse response obtained by converting the transfer function _HL to the time axis. On the other hand, in the plurality of multipliers 26, the impulse response at each time when the transfer function H _R is converted to the time axis is used as a coefficient. This allows
The FIR filter unit 20R, the input audio signal Sa relative to the transfer function H _R the time axis transformed impulse response is convolved output right audio signal Sbr is formed.

Returning to FIG. 1, the headphone device 10
Are the audio signals Sbl, S output from the signal processing circuit 13.
D / A converters 14L and 14R for converting br into analog signals, respectively, and amplifiers 15L and 15R for amplifying audio signals Sbl and Sbr converted into analog signals, respectively.
And headphones 16 to which the amplified audio signals Sbl and Sbr are respectively supplied.

The operation of the headphone device 10 shown in FIG. 1 will be described. The input audio signal Sa supplied to the input terminal 11 is converted into a digital signal by the A / D converter 12 and then supplied to the signal processing circuit 13. In the FIR filter units 20L and 20R of the signal processing circuit 13, impulse responses obtained by converting transfer functions H _L and H _R on the time axis with respect to the input audio signal Sa are convolved, respectively, and output left audio signals Sbl and
An output right audio signal Sbr is formed.

The audio signals Sbl and Sbr are converted to analog signals by D / A converters 14L and 14R, respectively, and then supplied to headphones 16 after being amplified by amplifiers 15L and 15R. Therefore, the headphones 1
Reference numeral 6 is driven by the audio signals Sbl and Sbr, and can localize the sound image by the input audio signal Sa outside the head. That is, when the listener M wears the headphones 16, FIG.
The state where the sound source S exists outside the head is reproduced as shown in FIG.

In this embodiment, as shown in FIG. 2, a delay unit 22 constituting a delay line of two FIR filter units 20L and 20R constituting a signal processing circuit 13 is shared. Therefore, the required number of delay units 22 can be significantly reduced, and the circuit scale and cost can be reduced. For example, when the delay unit 22 is constituted by a data RAM incorporated in a digital signal processing IC, the size and cost of the digital signal processing IC can be reduced. In addition, the mounting area can be naturally reduced and the power consumption can be reduced by reducing the scale of the digital signal processing IC.

FIG. 3 shows a configuration of a stereo out-of-head sound image localization type headphone device 30 as a second embodiment. The headphone device 30 localizes a sound image based on the input left audio signal and the input right audio signal outside the head.

First, the headphone device 3 will be described with reference to FIG.
The principle of 0 will be described. Source S _L each of the left and right ears of the listener M than H _LL, sound is transmitted through routes with H _LR transfer functions. Further, the sound source S respectively to the left and right ears of the listener M from _R H _{R L,} the sound through routes with H _RR transfer functions is transmitted. Therefore, in order to reproduce this state using headphones, an input audio signal Sal corresponding to the sound source S _L through a filter for implementing the transfer function H _LL with obtaining a left audio signal SBLL, said audio signal Sal with obtaining the right audio signal Sblr through a filter for implementing the transfer function H _LR, with obtaining a left audio signal Sbrl through a filter for implementing the transfer function H _RL input right audio signal Sar corresponding to the sound source S _R, the audio signal Sar
So as to obtain a right audio signal Sbrr through a filter for implementing the transfer function H _RR a. Then, the output left audio signal (Sb
ll + Sbrl) and the output right audio signal (Sblr + Sbrr) to drive the headphones.

Next, the configuration of the headphone device 30 of FIG. 3 will be described. The headphone device 30 includes an input terminal 31L to which an input left audio signal Sal is supplied, and an input right audio signal S
ar is supplied to the input terminal 31R, and the audio signals Sal and Sar
A / D converters 32L and 32R for converting digital signals into digital signals, respectively, and signal processing circuits 33L and 33R for performing filter processing on the audio signals Sal and Sar converted into digital signals.

The signal processing circuit 33L includes two FIs, similarly to the signal processing circuit 13 of the headphone device 10 shown in FIG.
It has an R filter section (see FIG. 2). Then, the convoluted impulse response generated by converting a transfer function H _LL in the time axis with respect to the audio signal Sal at one of the FIR filter section audio signal Sbll is formed, on the other hand of the FIR filter unit, the audio signal Sal right audio signal Sblr is formed a transfer function H _LR of the convolved impulse response generated by converting the time axis for.

The signal processing circuit 33R also has two FIs similarly to the signal processing circuit 13 of the headphone device 10 shown in FIG.
It has an R filter section (see FIG. 2). Then, the convoluted impulse response generated by converting a transfer function H _RL the time axis with respect to the audio signal Sar at one of the FIR filter section audio signal Sbrl is formed, on the other hand of the FIR filter unit, the audio signal Sar right audio signal Sbrr is formed a transfer function H _RR convolved time impulse response generated by converting the axis for.

Further, the headphone device 30 outputs the left audio signals Sbll, Sb output from the signal processing circuits 33L, 33R.
adder 3 for adding rl to obtain output left audio signal Sbl
4L, an adder 34R for adding the right audio signals Sblr and Sbrr output from the signal processing circuits 33L and 33R to obtain an output right audio signal Sbr, and D for converting the audio signals Sbl and Sbr into analog signals, respectively. / A converter 35L,
35R and audio signals Sbl and S converted to analog signals.
It has amplifiers 36L and 36R for amplifying br, respectively, and headphones 37 to which the amplified audio signals Sbl and Sbr are respectively supplied.

The operation of the headphone device 30 shown in FIG. 3 will be described. Input left audio signal S supplied to input terminal 31L
al is supplied to the signal processing circuit 33L after being converted into a digital signal by the A / D converter 32L. Then, the two FIR filter units of the signal processing circuit 33L convolve the impulse responses obtained by converting the transfer functions H _LL and H _LR on the time axis with respect to the audio signal Sal, respectively, and convolve the left audio signal S
bll and a right audio signal Sblr are formed.

The input left audio signal Sar supplied to the input terminal 31R is supplied to the signal processing circuit 33R after being converted into a digital signal by the A / D converter 32R.
Then, the two FIR filter units of the signal processing circuit 33R convolve the impulse responses obtained by converting the transfer functions H _RL and H _RR on the time axis with respect to the audio signal Sar, respectively, and convolve the left audio signal Sbrl and the right audio signal Sbrr is formed.

Then, the left audio signals Sbll and Sbrl are added by an adder 34L to obtain an output left audio signal Sbl, and the right audio signals Sblr and Sbrr are added by an adder 34R to obtain an output right audio signal Sbr. Can be These audio signals Sb
l and Sbr are D / A converters 35L and 35R, respectively.
Are converted to analog signals by the amplifiers 36L, 36
After being amplified by R, it is supplied to headphones 37. Therefore, the headphones 37 are driven by the audio signals Sbl and Sbr, and the input left audio signal Sal and the input right audio signal Sar
Can be localized outside the head.
That is, when the listener M wears the headphones 37, a state in which the sound sources S _L and S _R are outside the head as shown in FIG. 4 is reproduced.

In this embodiment, the signal processing circuit 3
Since the delay lines constituting the delay lines of the two FIR filter units constituting 3L and 33R are shared, the number of necessary delay units can be greatly reduced, and the circuit scale and cost can be reduced. it can.

FIG. 5 shows a configuration of a speaker device 40 as a third embodiment. This speaker device 40
Is to localize a sound image at an arbitrary position using two speakers.

First, referring to FIG.
The principle of will be described. If you are using the sound source S _L and the sound source S _R to reproduce the equivalent sound source S _O, the sound source S _L from the listener M left ear, respectively a transfer function to the right ear H _LL, H _LR, the sound source S _R Let H _RL and H _RR be the transfer functions from the sound source M to the left and right ears of the listener M, and H _OL and H _OR be the transfer functions from the sound source S _O to the left and right ears of the listener M, respectively. The sound source S _L is expressed as in equation (1), and the sound source S _R is expressed as in equation (2).

[0039]

(Equation 1)

Accordingly, an output left audio signal Sbl is obtained from the input audio signal Sao corresponding to the sound source S _O through a filter that realizes the transfer function part of the equation (1), and the audio signal Sao is converted to the transfer function of the equation (2). The output right audio signal Sbr is obtained through a filter that realizes the portion, and these audio signals Sbl, Sbl,
By driving two speakers arranged at the positions of the sound sources S _L and S _R by Sbr, the sound image by the audio signal Sao can be localized at the position of the sound source S _O.

Next, the configuration of the speaker device 40 shown in FIG. 5 will be described. The speaker device 40 receives the input left audio signal Sao.
, An A / D converter 42 for converting the audio signal Sao into a digital signal, and a signal processing circuit 43 for filtering the audio signal Sao converted into the digital signal. I have.

The signal processing circuit 43, like the signal processing circuit 13 of the headphone device 10 shown in FIG.
It has a filter section (see FIG. 2). And
In one FIR filter unit, an impulse response obtained by converting the transfer function part of the equation (1) into the time axis is convoluted with the audio signal Sao to form an output left audio signal Sbl, and in the other FIR filter unit, the audio signal Sao is output. The output right audio signal Sbr is formed by convolving the signal Sao with the impulse response obtained by converting the transfer function part of the equation (2) on the time axis.

Further, the speaker device 40 outputs the audio signal Sb
D / A converters 44L and 44R for converting l and Sbr into analog signals, respectively, and amplifiers 45L and 4A for amplifying audio signals Sbl and Sbr converted to analog signals, respectively.
5R, and a left speaker 46L and a right speaker 46R to which the amplified audio signals Sbl and Sbr are respectively supplied. Note that the speakers 46L, 46R is the sound source S _L with respect to the listener M, respectively, disposed in the position of S _R (see Figure 6).

The operation of the speaker device 40 shown in FIG. 5 will be described. The input audio signal Sao supplied to the input terminal 41 is A
After being converted into a digital signal by the / D converter 42, the digital signal is supplied to the signal processing circuit 43. Then, the two FIR filter units of the signal processing circuit 43 convolve the impulse responses obtained by converting the transfer function portions of the equations (1) and (2) into the time axis with respect to the audio signal Sao, and output the result. An audio signal Sbl and an output right audio signal Sbr are formed.

Then, the audio signals Sbll and Sbrl are converted into analog signals by D / A converters 44L and 44R, respectively, and further amplified by amplifiers 45L and 45R, and then supplied to speakers 46L and 46R. Therefore, the speakers 46L and 46R are driven by the audio signals Sbl and Sbr, and the sound image based on the input audio signal Sao can be localized at the position of the sound source So (see FIG. 6).

Also in this embodiment, the signal processing circuit 4
Since the two delay lines of the two FIR filter units constituting the third unit are commonly used, the number of necessary delay units can be significantly reduced, and the circuit scale and cost can be reduced.

In the speaker device 40 shown in FIG.
Although the sound image is localized at an arbitrary position by two speakers, the sound image may be localized at an arbitrary position by three or more speakers. In that case, the signal processing circuit will have FIR filter sections corresponding to the number of speakers, but since the input audio signals supplied to the delay lines of each FIR filter section are all common, The delay device that constitutes the delay line can be shared.

FIG. 7 shows a configuration of a speaker device 50 as a fourth embodiment. This speaker device 50
Is a device in which a surround effect is obtained by controlling the sound image localization position of a 5-channel audio signal using two speakers.

First, referring to FIG.
The principle of will be described. The speaker device 50 is connected to the listener M
In front of the left sound source S _L , the center sound source S _C and the right sound source S _R
Along with the think about the one in which was considered a left sound source S _BL and the right sound source S _BR to the rear of the listener M.

The sound source S _L and the sound source S If you use the _R to reproduce the equivalent sound source S _BL, sound source S _L from the listener M left ear, respectively, the transfer function to the right ear H _LL, H _LR, the left ear of the listener M from the sound source S _R, respectively H _RL the transfer function to the right ear, H _RR, further to the left ear of the listener M from the sound source S _BL,
Each transfer function reaching the right ear H _BLL, when the H _BLR, the sound source S _L is expressed as (3), the sound source S _R is expressed by the equation (4).

[0051]

(Equation 2)

[0052] Thus, the input audio signal SABL corresponding to the sound source S _BL (3) together with obtaining a left audio signal Sbll through a filter for implementing the transfer function part of the equation, the transfer function portion of the audio signal SABL (4) equation Are obtained through a filter that realizes the following equation, and these audio signals Sbll,
Source S _L by Sblr, by driving the two loudspeakers arranged at the position of S _R, it is possible to localize a sound image by the speech signals Sabl the position of the sound source S _BL.

[0053] In addition, if you use a sound source S _L and the sound source S _R equivalently to reproduce the sound source S _BR, the listener from the sound source S _BR M
Transfer functions to the left and right ears of H _BRL and H _BRR respectively
Then, the sound source S _L is expressed as in equation (5), and the sound source S _R
Is expressed as in equation (6).

[0054]

(Equation 3)

[0055] Thus, the input audio signal SABR corresponding to the sound source S _BR (5) together with obtaining a left audio signal Sbrl through a filter for implementing the transfer function part of the equation, the transfer function portion of the audio signal SABR (6) formula Is obtained through a filter that realizes the following expression, and these audio signals Sbrl,
By driving two speakers arranged at the positions of the sound sources S _L and S _R by Sbrr, it is possible to localize the sound image by the audio signal Sabr at the position of the sound source S _BR .

The input audio signal Sa corresponding to the sound source S _C
By attenuating c by, for example, 3 dB, and driving two speakers arranged at the positions of the sound sources S _L and S _R , respectively,
A sound image based on the audio signal Sac can be localized at the position of the sound source S _C. Next, the configuration of the speaker device 50 in FIG. 7 will be described. The speaker device 50 has an input terminal 51L to which an input left audio signal Sal is supplied, an input terminal 51C to which an input audio signal Sac is supplied, an input terminal 51R to which an input right audio signal Sar is supplied, and an input audio signal. An input terminal 51BL to which Sabl is supplied, an input terminal 51BR to which an input audio signal Sabr is supplied, and audio signals Sal, Sac, Sar, Sabl, and Sabr.
To A / D converters 52L, 52C, 52R, 52BL, and 52BR, respectively, for converting the signals into digital signals.

The speaker device 50 includes an attenuator 53 for attenuating the audio signal Sac converted into a digital signal by 3 dB, and an audio signal Sabl,
It has signal processing circuits 54BL and 54BR that respectively perform filter processing on Sabr.

The signal processing circuit 54BL includes two F-signals, similarly to the signal processing circuit 13 of the headphone device 10 shown in FIG.
It has an IR filter section (see FIG. 2). Then, in one FIR filter unit, the impulse response obtained by converting the transfer function part of the equation (3) into the time axis is convolved with the audio signal Sabl to form a left audio signal Sbll, and in the other FIR filter unit, A right audio signal Sblr is formed by convoluting the audio signal Sabl with an impulse response obtained by converting the transfer function portion of the equation (4) into a time axis.

Similarly to the signal processing circuit 13 of the headphone device 10 shown in FIG.
It has an IR filter section (see FIG. 2). Then, in one FIR filter unit, an impulse response obtained by converting the transfer function part of Expression (5) into the time axis is convoluted with the audio signal Sabr to form a left audio signal Sbrl, and in the other FIR filter unit, A right audio signal Sbrr is formed by convoluting the audio signal Sabr with an impulse response obtained by converting the transfer function part of Expression (6) into a time axis.

The speaker device 50 outputs the audio signal Sbl.
Adder 55B for adding left and Sbrl to obtain left audio signal Sol
L and the audio signals Sblr, Sbrr are added to obtain a left audio signal Sor
55L which adds the input left audio signal Sal converted into a digital signal, the audio signal Sac attenuated by the attenuator 53, and the above-described left audio signal Sol to obtain an output left audio signal Sbl. And an adder 56R that adds the input right audio signal Sar converted into a digital signal, the audio signal Sac attenuated by the attenuator 53, and the above-described right audio signal Sor to obtain an output right audio signal Sbr. I have.

The speaker device 50 outputs the audio signal Sb
D / A converters 57L and 57R that convert l and Sbr to analog signals, respectively, and amplifiers 58L and 5 that amplify audio signals Sbl and Sbr converted to analog signals, respectively.
8R, and a left speaker 59L and a right speaker 59R to which the amplified audio signals Sbl and Sbr are respectively supplied. Note that the speakers 59L and 59R are disposed at the positions of the sound sources S _L and S _R with respect to the listener M, respectively (see FIG. 8).

The operation of the speaker device 50 shown in FIG. 7 will be described. Input left audio signal Sal supplied to input terminal 51L
Is converted into a digital signal by the A / D converter 52L, and the input right audio signal Sar supplied to the input terminal 51R is converted into a digital signal by the A / D converter 52R. The input audio signal Sac supplied to the input terminal 51C
Is converted into a digital signal by the A / D converter 52L, and is further attenuated by 3 dB by the attenuator 53.

The input audio signals Sabl and Sabr supplied to the input terminals 51BL and 51BR are supplied to the signal processing circuits 54BL and 54BR after being converted into digital signals by the A / D converters 52BL and 52BR, respectively. In the two FIR filter units of the signal processing circuit 54BL, equations (3) and (4) are applied to the audio signal Sabl, respectively.
The impulse response obtained by converting the transfer function part of the equation into the time axis is convolved to form the left audio signal Sbll and the right audio signal Sblr. In the two FIR filter units of the signal processing circuit 54BR, each of the audio signals Sabr is given by the following equation (5).
The impulse response obtained by converting the transfer function part of the equation (6) to the time axis is convoluted to produce a left audio signal Sbrl and a right audio signal Sbrr.
Is formed.

Then, the input left audio signal Sal, the attenuator 53
The left audio signal Sol (Sbll + Sbrl) output from the adder 55BL is added to the adder 56 in addition to the audio signal Sac attenuated by
L to form an output left audio signal Sbl. In addition to the input right audio signal Sar, the audio signal Sac attenuated by the attenuator 53, and the right audio signal Sor (Sblr + Sbrr) output from the adder 55BR. The output right audio signal Sbr is formed by the addition by the adder 56R. These audio signals Sbl and Sbr are respectively supplied to a D / A converter 57.
L and 57R convert the signal into an analog signal.
After being amplified by 8L and 58R, the speakers 59L and 59R are amplified.
Supplied to R.

Therefore, the speakers 59L and 59R are
Since each is driven by audio signals Sal and Sar,
The sound images based on the audio signals Sal and Sar are sound sources S _L and S _R , respectively.
To the position of. The speakers 59L and 59R are
Because each driven by voice signals Sac attenuated by 3 dB, the sound image by the speech signal Sac is localized at the position of the sound source S _C. The speaker 59L, 59R, respectively audio signals SBLL, to be driven by Sblr, the sound image by the speech signals Sabl is localized at the position of the sound source S _BL. Further, the speakers 59L and 59R output the audio signals S
brl, because it is driven by Sbrr, the sound image by the speech signals Sabr is localized at the position of the sound source S _BR.

[0066] localization Thus, in the speaker apparatus 50 of FIG. 7, the audio signals Sal, Sar, Sac, SABL, the sound image by Sabr is, the sound source S _{L respectively, S R, S C, S} BL, the position of S _BR (See FIG. 8). Therefore, two speakers 59
The surround effect can be obtained by controlling the sound image localization position of the 5-channel audio signal using L and 59R.

Also in this embodiment, the signal processing circuit 5
Since the delay lines constituting the delay lines of the two FIR filter units constituting 4BL and 54BR are shared, the number of necessary delay units can be greatly reduced, and the circuit scale and cost can be reduced. it can.

In the above embodiment, all the delay units constituting the delay lines of the plurality of FIR filter units are commonly used. However, only a part of the delay units may be used in common. Can be reduced.

[0069]

According to the present invention, a part or all of the delay units constituting the delay lines of the plurality of FIR filter units are made common, and the number of necessary delay units can be greatly reduced. The scale and cost can be reduced. Therefore, when the delay device is configured by a data RAM incorporated in the digital signal processing IC, the scale of the digital signal processing IC can be reduced, and the cost can be reduced. In addition, since the scale of the digital signal processing IC is reduced, there is an advantage that a mounting area can be reduced and power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an out-of-head sound image localization type headphone device according to a first embodiment.

FIG. 2 is a circuit connection diagram illustrating a configuration of a signal processing circuit.

FIG. 3 is a block diagram illustrating a configuration of a stereo out-of-head sound image localization type headphone device according to a second embodiment.

FIG. 4 is a diagram for explaining the principle of the stereo out-of-head sound image localization type headphone device of FIG. 4;

FIG. 5 is a block diagram illustrating a configuration of a speaker device according to a third embodiment.

FIG. 6 is a diagram for explaining the principle of the speaker device of FIG. 5;

FIG. 7 is a block diagram illustrating a configuration of a speaker device according to a fourth embodiment.

FIG. 8 is a diagram for explaining the principle of the speaker device of FIG. 7;

FIG. 9 is a diagram showing a configuration example of a conventional out-of-head sound image localization type headphone device.

FIG. 10 is a diagram for explaining the principle of the headphone device of FIG. 9;

FIG. 11 is a circuit connection diagram illustrating a configuration of a signal processing circuit.

[Explanation of symbols]

10 ・ ・ ・ Out-of-head sound image localization type headphone device, 13 ・ ・ ・
Signal processing circuit, 16 ... headphones, 20L, 20R
... FIR filter part, 22 ... Delay device, 23,2
6 Multipliers, 24, 27 Adders, 30
Stereo out-of-head sound image localization type headphone device, 33L, 33
R: signal processing circuit, 34L, 34R: adder,
37 ... headphone, 40 ... speaker device, 43
... Signal processing circuit, 46L ... Left speaker, 46R
... Right speaker, 50 ... Speaker device, 53 ...
.Attenuator, 54BL, 54BR ... signal processing circuit, 5
5BL, 55BR, 56L, 56R ... adder, 59
L: Left speaker, 59R: Right speaker

Claims (7)

[Claims] 1. A plurality of FIR filter sections, wherein the plurality of FIR filter sections each include a delay line composed of a plurality of delay units connected in series, and a coefficient applied to a signal of each tap of the delay line. , And an adder for adding the output signals of the plurality of multipliers, and a part or all of the delay units constituting the delay lines of the plurality of filter units are shared. A featured FIR filter. 2. The apparatus according to claim 1, wherein said plurality of FIR filter sections include two FIR filter sections.
2. The FIR filter according to claim 1. 3. A first and a second FIR filter section for reproducing two systems of impulse responses from a sound source previously measured or calculated to a left ear and a right ear of a listener. Signal processing means for convolving the two impulse responses with respect to the input audio signal in the second FIR filter unit to obtain an output left audio signal and an output right audio signal, respectively; In the headphone device, a headphone is driven by a signal to localize a sound image based on the input audio signal outside the head.
And a part of or all of the delay units constituting the delay line of the second FIR filter unit are shared. 4. A first and a second FIR filter section for reproducing two impulse responses from a left sound source to a left ear and a right ear of a listener, which are measured or calculated in advance. And first signal processing means for convolving the two impulse responses with respect to the input left audio signal by the second FIR filter unit to obtain a first left audio signal and a first right audio signal, respectively. There are third and fourth FIR filter sections for reproducing two impulse responses from the right sound source to the left ear and the right ear of the listener calculated by measurement or calculation, and the third and fourth FIR filters are provided. The second unit obtains a second left audio signal and a second right audio signal by convolving the above two impulse responses with the input right audio signal.
Signal processing means, first adding means for adding the first and second left audio signals to obtain an output left audio signal, and adding the first and second right audio signals to output right audio. A second adding means for obtaining a signal, wherein the headphone is driven by the output left audio signal and the output right audio signal so that the sound image based on the input left audio signal and the input right audio signal is localized outside the head. In the apparatus, a part or all of the delay units constituting the delay lines of the first and second FIR filter units are made common, and the delay units constituting the delay lines of the third and fourth FIR filter units are provided. A headphone device characterized in that part or all of the headphone is shared. 5. A signal processing means having a plurality of FIR filter sections and convolving a plurality of impulse responses with respect to an input audio signal by the plurality of FIR filter sections to obtain a plurality of output audio signals. A speaker device configured to drive a plurality of speakers with the output audio signals of the plurality of systems so as to localize a sound image based on the input audio signal at an arbitrary position, wherein a delay constituting a delay line of the plurality of FIR filter units is provided. A speaker device characterized in that some or all of the devices are common. 6. The apparatus according to claim 5, wherein said plurality of FIR filter sections include two FIR filter sections.
The speaker device according to claim 1. 7. A multi-channel audio signal of at least three channels or more is reproduced by two speakers arranged in front of a listener, and a predetermined audio signal of the multi-channel audio signal is reproduced. Signal processing means having first and second FIR filter units for respectively convolving the two systems of impulse responses to obtain two systems of output audio signals, and using the two systems of output audio signals to control the two speakers. In a speaker device which is driven to localize a sound image based on the predetermined audio signal outside the two speakers or behind a listener, a delay constituting a delay line of the first and second FIR filter units A speaker device characterized in that some or all of the devices are common.