JPH064076A - Timbre generating device - Google Patents

Abstract

PURPOSE:To obtain proper frequency characteristics for various harmonic overtones of a digital tone sound signal corresponding to the pitch of the digital musical tone signal. CONSTITUTION:While delay is accumulated in a feedback loop, a cyclic filter arithmetic means provided with variable length delay lines 36 and 46 filters the musical tone signal from an input part 20 by using the filter coefficient supplied from a filter coefficient supply means 50. A pitch detecting means 52 detects pitch information corresponding to the pitch of the musical tone signal and a delay time setting means 54 sets a delay time for delay lines 36 and 46 according to the detected pitch. A filter coefficient supply means 50 is so constituted as to vary the filter coefficient supplied to the cyclic filter arithmetic means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming a tone color in a tone signal, and more particularly to an apparatus using a digital filter having a plurality of delay means.

[0002]

2. Description of the Related Art Conventionally, a comb filter has been used as a tone color forming device having a delay means.
There is something like. In this comb filter, a digital musical tone signal is supplied from an input section 12 to an adder 14, and the output of the adder 14 is a variable length delay line 16
Is delayed by, the multiplier 15 multiplies the feedback coefficient, and the result is fed back to the adder 14. The output of the adder 14 is output from the output unit 18.

This comb filter has the characteristics shown in FIG. 10 when the delay signal is added to the input signal in the adder 14, and the characteristics shown in FIG. 11 when the delay signal is subtracted from the input signal in the adder 14. . In addition,
10 and 11 show the characteristics when the sampling frequency is 48 KHz, the delay time in the variable length delay line 16 is the same as 24 sampling cycles, and the feedback coefficients are 0.8 and -0.6, respectively. The characteristics are such that 2 KHz and an integral multiple thereof are passed or blocked.

[0004]

In the above comb filter, for example, the fundamental tone and its harmonics are passed as shown in FIG. 10, or the fundamental tone and its harmonics are cut off as shown in FIG. You can However, when utilizing such a characteristic, when performing correction or timbre formation on a harmonic series of a certain digital musical tone signal, it is only possible to pass or block the overtone, and various harmonic overtones are obtained. On the other hand, an appropriate frequency characteristic could not be obtained. For example, when it is desired to block only the fundamental tone and its overtone, the bottom portion of each bottom is not steep in the characteristics shown in FIG. 11, so that signals around the fundamental tone and its overtone are also blocked. When the fundamental tone and its overtones and the non-integer-order overtones around them are passed, the non-integer-order overtone cannot be sufficiently passed because the peak portion is steep in the characteristic shown in FIG. Further, in the conventional comb filter, there is a problem that it is not possible to freely set the bandwidth to pass or the bandwidth to block.

[0005]

In order to solve the above-mentioned problems, in the present invention, input means for inputting a tone signal, and
A plurality of delaying means, multiplying means, and adding means are provided, and filter calculating means for performing a filter operation on the tone signal from the input means, filter coefficient supplying means for supplying a filter coefficient to the filter calculating means, and the tone It is provided with pitch information input means for inputting pitch information corresponding to the pitch of the signal, and delay time setting means for setting a delay time in each of the delay means based on the input pitch information. Further, the filter coefficient supply means may be configured to change the filter coefficient.

[0006]

According to the present invention, it is possible to obtain a frequency characteristic which cannot be obtained by the conventional comb filter. That is,
By setting the delay means of the filter calculation means in correspondence with the pitch of the input musical tone signal, it is possible to select a plurality of frequency components having a specific relationship with the pitch of the input musical tone signal, and to set the filter coefficient of the filter calculation means. By controlling, the characteristics of the selected frequency components can be controlled collectively. For example, in the simplest case,
It is possible to set the delay means so as to pass the fundamental wave component of the input musical tone signal and its overtone component, and collectively set the width of the pass band by the filter coefficient.

[0007]

In this embodiment, a digital musical tone signal supplied from an input unit 20 is filtered and output from output units 22, 24 and 26. The digital musical tone signal from the input unit 20 is After being multiplied by an appropriate coefficient in the multiplier 28, it is supplied to the adder 30. This adder 30
The output of is multiplied by the filter coefficient B in the multiplier 32, and is supplied to the adder 34. The output of the adder 34 is supplied to the variable length delay line 36.

The output of the delay line 36 is the adder 3
4, the multiplier 38 multiplies the filter coefficient P, and the multiplier 40 feeds it back to the adder 30. Further, the output of the delay line 36 is multiplied by the filter coefficient B in the multiplier 42 and supplied to the adder 44.

The output of the adder 44 is supplied to the variable length delay line 46, and the output of the delay line 46 is fed back to the adder 44. The output of the adder 46 is multiplied by the filter coefficient F in the multiplier 48 and fed back to the adder 30 via the adder 40.

The output of the adder 30 is supplied to the output unit 22, the output of the adder 34 is supplied to the output unit 24, and the output of the adder 44 is supplied to the output unit 26.

The filter coefficient B to the multipliers 32 and 42, the filter coefficient P to the multiplier 38, and the filter coefficient F to the multiplier 48 are supplied from the filter coefficient supply means 50.
This filter coefficient supply means stores the filter coefficients B, P and F of various values, and the filter coefficients B, P and F of the values selected by the selection signal respectively correspond to the multipliers 32, 38 and 42. , 48.

The digital musical tone signal from the multiplier 38 is also supplied to the pitch detecting means 52, which detects the pitch of the digital musical tone signal and supplies it to the delay time setting means 54. Delay time setting means 54
Sets the delay time of the variable length delay lines 36 and 46 according to the pitch detected by the pitch detecting means 52.

In practice, the variable length delay lines 36, 4
6 is composed of a shift register having a plurality of stages, and the delay time setting means 54 determines from which stage (delayed output stage) of these variable length delay lines the output is to be taken out.

When the delay output stage of the variable length delay line 36 is n and the delay output stage of the variable length delay line 46 is m, the transfer function H1 (Z) of the output of the output unit 22 and the output unit 2 are shown.
The output transfer function H2 (Z) of the output No. 4 and the transfer function H3 (Z) of the output unit 26 are expressed by Equations 1, 2 and 3, respectively.

[0015]

[Equation 1]

[Equation 2]

[Equation 3]

Assuming that the delay output stages of the variable length delay lines 36 and 46 are 1 and the filter coefficient F is -1 in FIG. 1, transfer functions H1 (Z) and H2 are obtained.
(Z) and H3 (Z) are H11 (Z), H21 (Z), and H31 (Z) shown by the equations 4, 5, and 6. However, α is 2 + BP−B ² and β is −BP-1.

[0017]

[Equation 4]

[Equation 5]

[Equation 6]

H11 (Z) is a second-order high-pass filter, H21 (Z) is a second-order band-pass filter, H31.
(Z) represents the transfer function of each of the second-order low-pass filters, from which the output unit 22 has the high-pass filter frequency characteristic, the output unit 24 has the band-pass filter frequency characteristic, and the output unit 26 has the high-pass filter frequency characteristic. I understand.

First, it is assumed that the tone color forming apparatus of FIG. 1 operates at a sampling frequency of 48 KHz, and the delay output stages n and m set in the variable length delay lines 36 and 46 are set to the same number. The delay output stage M is set so that the relationship between the delay output stage M set in the variable length delay lines 36 and 46 and the frequency Fi of the input musical tone signal is M = 48000 / Fi. This relationship can be changed appropriately. 2 and 3
From the above equation, the delay output stage M of the variable length delay lines 36 and 46 is set to 24 and the filter coefficients B, P and F are characteristics when an input musical tone signal having a frequency of 2 KHz is input.
Are frequency characteristics when the values are set to 0.5, -1.4, and -1.0, respectively. 2 shows the characteristics of the output unit 26, and FIG. 3 shows the characteristics of the output unit 22. FIG. 2 shows a characteristic of passing a fundamental tone of 2 KHz and its overtone, and FIG. 3 shows a characteristic of cutting off the fundamental tone of 2 KHz and its overtone. Then, by changing the filter coefficient B, it is possible to change the bandwidth for passing or blocking the fundamental and overtones.
This is an effect that cannot be obtained by the conventional comb filter.

FIGS. 4, 5 and 6 show the filter coefficient B.
For showing the change of the frequency characteristic when the frequency is changed, the sampling frequency is 48 KHz, the delay output stages n and m of the variable length delay lines 36 and 46 are 24, and the filter coefficients P and F are −, respectively. 1.4,-
The characteristics of the output unit 26 when the filter coefficient B is changed by setting 1.0 is shown. The value of the filter coefficient B is set to 0.20 in FIG. 4, 0.67 in FIG. 5, and 0.10 in FIG. Thus, the filter coefficient B
The width of the pass band is collectively changed by changing the value of. By changing the width of this pass band, the passing amount of the non-integer harmonics can be controlled.

In the above embodiment, when the tone signal is set to be output from the output unit 26, the filter coefficient B is used to pass the width of the frequency components around the fundamental frequency and the frequency component of an integral multiple (sideband). ) Can be controlled. When the output unit 24 is set to output a tone signal, the filter coefficient B can control the width (sideband) of blocking the frequency component around the fundamental frequency and the frequency component of an integral multiple thereof. .

7 and 8, the sampling frequency is 48
An example of the frequency characteristic when the filter coefficient and the output unit are changed is shown with KHz and the delay outputs n and m of the variable length delay lines 36 and 46 being 12. FIG. 7 shows the characteristics of the output unit 24 when the filter coefficients B, P, and F are 0.4, -1.0, and -1.0. FIG. 8 shows filter coefficients B, P,
Output unit 2 when F is 0.6, -0.5, -1.0
6 characteristics. As described above, by setting the filter coefficient and selecting the output unit, it is possible to set more complicated characteristics centering on the frequency component having a specific relationship with the pitch of the input musical tone signal.

As described above, the setting of the characteristics by the variable length delay line and the filter coefficient can be set independently of each other, and the frequency relationship is the variable length delay line, and the filter coefficient is different for each. It is very easy to set because it is only necessary to consider what kind of characteristics in the band, for example, each harmonic overtone is desired.

In the above example, the delay output stages of the variable length delay lines 36 and 46 have the same number of stages.
For example, the number of stages of the variable length delay line 46 may be set to a stage number which is an integer fraction of the number of delay output stages of the variable length delay line 36. In this case, outputs having frequency characteristics different from those described above are obtained from the output units 22, 24 and 26, respectively.

In the above embodiment, the variable length delay lines 36 and 46 are delayed by 24 and 12, which are integer sampling numbers. However, depending on the pitch detected by the pitch detecting means 52, a decimal number is included. It may require a delay in the number of samples. For example, if the digital tone signal is 2.6 KHz, in the above example, the delay output stage of the variable length delay lines 36 and 46 must be 36.2. In such a case, the delay of the sampling number including the decimal is output by interpolation. For example, in the case of linear interpolation, the difference between the output signal of the 36th stage and the output signal of the 37th stage is multiplied by 0.2, and the product of this multiplication value and the output of the 36th stage is added by the adder 34. , And may be supplied to the multiplier 38.

In the above embodiment, the tone digital signal supplied to the input section 20 has been described as a single tone.
For example, when the present invention is applied to an electric guitar equipped with a six-string independent type pickup that independently detects the string vibration for each string, a musical tone digital signal obtained based on a signal from the pickup corresponding to each string. The tone color forming devices shown in the above embodiments may be provided for each of them, and the signals from these tone color forming devices may be combined. In the above description, the cyclic filter has been described, but the present invention is not limited to the above embodiment, and any cyclic or non-cyclic filter provided with a plurality of delay means may be used.

[0027]

As described above, according to the present invention, the filter means provided with the plurality of delay means is used, the delay time of the delay means is set in accordance with the pitch of the input musical tone signal, and the filter is further filtered. Since the characteristic is set by the coefficient, the characteristic can be easily set, and the characteristic of the frequency component having a specific relationship with the pitch of the input musical tone signal can be changed. It is possible to make fine changes that cannot be obtained with the comb filter of.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a tone color forming apparatus according to the present invention.

FIG. 2 is a frequency characteristic diagram of an output section 26 of the embodiment.

FIG. 3 is a frequency characteristic diagram of the output unit 22 of the same embodiment.

FIG. 4 is a frequency characteristic diagram of the output unit 26 when the filter coefficient B is 0.2 in the embodiment.

FIG. 5 is a frequency characteristic diagram of the output unit 26 when the filter coefficient B is set to 0.67 in the embodiment.

FIG. 6 is a frequency characteristic diagram of the output unit 26 when the filter coefficient B is 0.1 in the embodiment.

FIG. 7 is a frequency characteristic diagram of the output section 24 when the filter coefficient P is 1.0 in the embodiment.

FIG. 8 is a frequency characteristic diagram of the output unit 26 when the filter coefficient P is 0.5 in the embodiment.

FIG. 9 is a block diagram of a comb filter used as a conventional tone color forming device.

10 is a frequency characteristic diagram of the comb filter of FIG.

FIG. 11 is a frequency characteristic diagram of FIG.

[Explanation of symbols]

 20 Input Unit 22 24 26 Output Unit 30 Adder 32 Multiplier 34 Adder 36 Variable Length Delay Line 38 Multiplier 40 Adder 42 Multiplier 44 Adder 46 Variable Length Delay Line 48 Multiplier 50 Filter Coefficient Supplying Means 52 Pitch Detection Means 54 Delay time setting means

Claims (2)

[Claims] 1. A filter calculation means for providing a musical tone signal, an input means, a plurality of delay means, a multiplication means and an addition means for performing a filter calculation on the musical tone signal from the input means, and this filter calculation means. Filter coefficient supply means for supplying a filter coefficient to the multiplication means, pitch information input means for inputting pitch information corresponding to the pitch of the tone signal, and delay time for each delay means based on the input pitch information. And a delay time setting means for setting the above. 2. The tone color forming apparatus according to claim 1,
A tone color forming apparatus, wherein the filter coefficient supply means is configured to change the filter coefficient.