JP3287970B2 - Method and apparatus for adding reverberation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for adding reverberation using an impulse response measured in a sound field.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a configuration of a conventional reverberation adding apparatus. In FIG. 2, reference numeral 101 denotes a signal source such as music, and reference numerals 102 to 104 denote signal sources 10.
This is an FIR filter that changes the signal from the signal No. 1 to desired characteristics. 105 to 107 are FIR filters 102 to 10
An amplifier for amplifying a signal having desired characteristics in 4; 108
To 110 are timbre control filters for changing the timbre of the signals amplified by the amplifiers 105 to 107, 111 is an adder for adding the outputs of the timbre control filters 108 to 110, 112
Is a controller for controlling the amplification factors of the amplifiers 105 to 107, 1
13 is an amplifier for amplifying the output of the adder 111, 114 is a speaker connected to the amplifier 113, 115 is a listener,
A reproduction sound field 116 forms a desired sound field in which the speakers 114 are arranged, and forms an optimum sound field in both ears of the listener 115.

Next, the operation of the reverberation sound adding apparatus according to the above-mentioned conventional example will be described with reference to FIG. The FIR filters 102 to 104 are configured to have the same reverberation characteristics as an input signal based on an impulse response measured in a sound field where reproduction is desired, such as a theater. That is, the signal output from the signal source 101 is convolved by the FIR filters 102 to 104, and a reverberation sound is added. The outputs of the FIR filters 102 to 104 are amplified by the amplifiers 105 to 107, and the reverberation time is changed. The timbre of the output signals of the amplifiers 105 to 107 is controlled by timbre control filters 108 to 110. The outputs of the timbre control filters 108 to 110 are added in an adder 111, amplified in an amplifier 113, and then supplied to a speaker 114 in a reproduced sound field 116. In the reproduction sound field 116, the listener 115 receives a sound wave radiated from the speaker 114. In this way,
Conventionally, using the measured impulse response,
The reverberation time can be changed for the input signal.

[0004]

However, in the above-described conventional reverberation adding apparatus, there is a problem that the reverberation time can be changed, but it is not possible to change the reverberation time frequency characteristic. Was.

The present invention has been made to solve such a conventional problem, and it is possible to change a reverberation time to a desired value by using an impulse response measured in a sound field, and to realize a reverberation time. An object of the present invention is to provide an excellent reverberation sound adding method and apparatus capable of changing frequency characteristics.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an N number of N signals obtained by dividing an impulse response measured in advance on a time axis based on a delay time of each pulse. Is divided into M bands, and when only one band among the M bands is focused on at the output of each band, the amplification factors are controlled so as to be different depending on the time window. The reverberation time frequency characteristics can be changed.

The present invention also divides a signal from an arbitrary signal source into N pieces on a time axis based on a delay time of each pulse extracted from an impulse response measured in a sound field. N FIR filters for generating reverberation signals, and N filters
N amplifiers for individually amplifying the reverberation signals generated by the FIR filters of
A first controller for individually controlling the amplification factors to be amplified;
N amplifiers connected to the outputs of the amplifiers, M band splitters respectively connected to the outputs of the N generators, and M filters which are the outputs of the M band splitters Amplifiers for individually amplifying the reverberation signals of the respective amplifiers, a second controller for individually controlling the amplification factors of the M amplifiers, an adder for adding the outputs of the M amplifiers, and an adder those having an amplifier for outputting to the speaker amplifies the output.

[0008]

According to the present invention, it is possible to obtain a desired reverberation sound by changing the reverberation time of a reverberation sound to be added to an input signal and to individually control timbres. By changing the reverberation time frequency characteristics of the signal stepwise, desired reverberation frequency characteristics can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIG. FIG. 1 is a block diagram showing a configuration of a reverberation sound adding apparatus according to an embodiment of the present invention. In FIG.
Reference numeral 11 denotes a signal source such as music. Reference numerals 12 to 14 denote N FIR filters which generate N reverberation signals by dividing the time axis by N based on the delay time of each pulse extracted from the impulse response measured in the sound field. Reference numerals 15 to 17 denote N first amplifiers A for individually amplifying the N reverberation signals, respectively, and reference numeral 30 denotes N amplifiers 15 to 1.
7 is a first controller A for individually controlling the amplification factors. 1
Reference numerals 8 to 20 denote N timbre control filters connected to the outputs of the N amplifiers 15 to 17, and 21 to 24 denote M bands connected to the outputs of the N timbre control filters 18 to 20, respectively. This is a division filter. 25 to 28 is M
M second amplifiers B for individually amplifying the M reverberation signals output from the plurality of band division filters 21 to 24, respectively, and 31 individually indicates the amplification factors of the M amplifiers 25 to 28. This is the second controller B for controlling. 29 is each time window 3
An adder adds the outputs of the M amplifiers 25 to 28 in 9 to 41, an amplifier 32 amplifies the output of the adder 29 and outputs the output to the speaker 33, 34 is a listener,
35 is a reproduction sound field. Further, M band division filters 21 to 24 and M amplifiers 25 to 28 respectively
The number of reverberation time frequency characteristic change units 36 to 38 is configured.

As will be described later, the characteristics of the FIR filters 12 to 14 are changed so as to have different reverberation times based on, for example, impulse responses in a sound field desired to be reproduced. The amplifiers A15 to A17 are connected to the outputs of the FIR filters 12 to 14, respectively, and can independently change the gain under the control of the first controller A30. Therefore, the reverberation time can be changed by changing the amplification factor of the amplifier A by the time window. The outputs of the amplifiers A15 to A17 are connected to timbre control filters 18 to 20, and timbres are individually controlled.

The j-th band division filter and the second amplifier B in the i-th time window can be generally expressed as a band division filter [i, j] and an amplifier B [i, j].
The reverberation time-frequency characteristic can be changed by independently controlling the amplification factor of [i, j] by the second controller B31 so as to obtain a desired reverberation time-frequency characteristic.

All outputs of the amplifiers B in the reverberation time frequency characteristic changing units 36 to 38 are added by an adder 29 and further amplified by an amplifier 32 to a desired size. The output of the amplifier 32 is supplied to a speaker 33 of a reproduction sound field 35. In the reproduction sound field, a listener 34 receives a sound wave radiated from the speaker 33.

Next, the operation of the above embodiment will be described in more detail. In FIG. 1, an output signal from a signal source 11 is input to N FIR filters 12 to 14, and each reverberation time characteristic of each of the FIR filters 12 to 14 is, as described below, an actual sound field. It is determined from the pulse train extracted from the measured impulse response.

The method of extracting a pulse train may be, for example, a method using a known inverse filter process, a method of selecting a pulse train in the order of large amplitude, or a method of detecting the maximum value of the amplitude while performing mask processing. Good. The density of the pulse train needs to be 200 taps or more per 100 ms.

Next, a method of generating an FIR filter will be described. The pulse train obtained by the above method is divided for each duration TW of the time window and assigned to each of the N FIR filters, so that each of the N filters generates the same reverberation time, that is, a reverberation sound. Be composed.
Note that the time window TW may be set to 100 ms or less.
The outputs of the FIR filters 12 to 14 having different reverberation times are input to the amplifiers A15 to A17, respectively.

Here, assuming that the reverberation time of the pulse train is RTp and the desired reverberation time is RTd (where RTp> RT)
d), amplifier A [i] (i = 1, 2, 3, 4,...,
The amplification factor α [i] set in N) is obtained by the following equation (Equation 1).

[0017]

(Equation 1)

The timbres of the outputs of the amplifiers A15 to A17 are controlled by timbre control filters 18 to 20, respectively. The characteristic of the timbre control filter [i] (i = 1, 2, 3, 4,..., N) has a desired reverberation time frequency RT (f) (f is a frequency).
, It is assumed that the power spectrum p [f, i] is approximated by the following equation (Equation 2).

[0019]

(Equation 2)

The j-th band division filter and the amplifier B in the i-th time window generally have a band division filter [i,
j] and the amplifier B [i, j]. Where RTc
[J] is a coefficient to be changed in the band by RTd (the reverberation time of the band is obtained by multiplying RTd by RTc [j]), and the amplification factor β [i, j] in the amplifier B [i, j]. j] is obtained by the following equation (Equation 3).

[0021]

(Equation 3)

All outputs of the amplifiers B in the reverberation time frequency characteristic changing units 36 to 38 are added by an adder 29 and further amplified by an amplifier 32 to a desired size. The output of the amplifier 32 is supplied to a speaker 33 of a reproduction sound field 35. In the reproduction sound field, the sound wave radiated from the speaker 33 is
Listens.

As described above, according to the present embodiment, the amplifier B
By independently controlling the amplification factor of [i, j] by the controller B so as to obtain a desired reverberation time frequency characteristic, the reverberation time frequency characteristic can be changed.

The band division filter in this embodiment can be simply composed of two components, a low-pass filter and a high-pass filter. It may be composed of three, may be composed of a low-pass filter, a plurality of band-pass filters, and a high-pass filter, or may be composed of only a plurality of band-pass filters. Further, the above-mentioned band division filter may be constituted by 1/3 octave band or 1 octave band.

[0025]

As is apparent from the above description, the present invention provides N reverberation sounds obtained by dividing the previously measured impulse response into N on the time axis based on the delay time of each pulse. Each signal is divided into M bands, and when only one of the M bands is focused on in the output of each band, the amplification factor is controlled so as to be different depending on the time window. The time can be changed to a desired value, the reverberation time-frequency characteristics can be changed, and a desired sound field can be reproduced in a wide range.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a reverberation adding apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a conventional reverberation adding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Signal source 12 FIR filter (1) 13 FIR filter (2) 14 FIR filter (N) 15 Amplifier A (1) 16 Amplifier A (2) 17 Amplifier A (N) 18 Tone control filter (1) 19 Tone control filter (2) 20 Tone control filter (N) 21 Band division filter (1) 22 Band division filter (2) 23 Band division filter (M-1) 24 Band division filter (M) 25 Amplifier B (1) 26 Amplifier B ( 2) 27 amplifier B (M-1) 28 amplifier B (M) 29 adder 30 controller A 31 controller B 32 amplifier 33 speaker 34 listener 35 reproduced sound field 36 reverberation time frequency characteristic changing unit (1) 37 reverberation time frequency characteristic changing unit (2) 38 reverberation time frequency characteristic changing unit (N) 39 time window (1) 40 time window (2) 41 time window (N)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-167700 (JP, A) JP-A-6-149276 (JP, A) JP-A-5-232979 (JP, A) 323987 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G10H 1/00

Claims (2)

(57) [Claims] An N reverberation signal obtained by dividing N in the time axis from a previously measured impulse response based on a delay time of each pulse is divided into M bands, and each band is divided into M bands. A reverberation sound adding method in which the amplification factor is controlled to be different depending on the time window when only one of the M bands is focused on the output of the reverberation sound, so that the reverberation time-frequency characteristics of the signal can be changed stepwise. 2. A signal from an arbitrary signal source is divided into N on a time axis based on a delay time of each pulse extracted from an impulse response measured in a sound field, and N reverberation sound signals are obtained. N FIR filters for generating the FIR
N amplifiers for individually amplifying the reverberation signal generated by the filter, and amplification by the N amplifiers
A first controller for individually controlling the amplification factors to be applied;
N timbre control filters connected to the outputs of the amplifiers, M band division filters respectively connected to the outputs of the N timbre control filters, and outputs of the M band division filters. M amplifiers for individually amplifying the M reverberation signals, a second controller for individually controlling the amplification factors of the M amplifiers, and an adder for adding the outputs of the M amplifiers And an amplifier for amplifying the output of the adder and outputting the amplified output to a speaker.