JP2519441B2 - Chorus effect device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chorus effect device that adds a chorus effect by using a device that changes the pitch of an input audio frequency signal.

<Prior Art> Conventionally, as an apparatus for changing the pitch, for example, there is one disclosed in Japanese Patent Laid-Open No. 184298/1985. As shown in FIG. 4, an audio frequency signal, for example, a voice signal is supplied as an input signal to an analog / digital converter 4 via a low pass filter 2 to be converted into a digital signal, and this digital signal is written. writing the digital memory 6 in synchronism with the clock signal f _o, in synchronization with the read clock signal f _v of a frequency different from the write clock signal f _o, reads out sequentially the digital signal from the digital memory 6, a digital-to-analog converter 8 And a low-pass filter 10 to re-convert it into an output audio signal and output it. The pitch f ₁ of this output audio signal is f ₂ when the pitch of the input signal is Becomes Therefore, according to this pitch changing device, the pitch of the input audio frequency signal can be changed according to the pitch changing amount P (= f _v / f _o ).

<Summary of the Invention> The present invention is intended to provide a novel chorus effect device using the above-mentioned pitch changing device, and provides a pitch detecting means for detecting the pitch of an audio frequency signal and a plurality of different scale signals. Inputting means, control means for determining a plurality of pitch conversion amounts based on a plurality of pitches detected by the pitch detecting means and a plurality of pitches respectively corresponding to the plurality of input scale signals, and the plurality of A plurality of pitch conversion means for converting the pitch of the audio frequency signal according to the pitch conversion amount. The plurality of different scale signals can be input from a keyboard for performing a performance operation, or can be input from a sequencer. Further, the plurality of pitch conversion means can be realized by operating one pitch conversion device in a time division manner.

<Operation> Assuming that the pitch of the input audio frequency signal is f ₂ and the pitch represented by the scale signal is f ₁ , the control means sets the pitch conversion amount P.
Determined as f ₁ / f ₂ and supply it to the pitch conversion means. The pitch conversion means sets the pitch f _{3 of the} output signal to f ₃ = Pf ₂ = (f ₁ / f ₂ ) * f ₂ = f ₁ according to the pitch conversion amount f ₁ / f ₂ . That is, the pitch of the input audio frequency signal is
It means that the pitch is changed to the pitch f ₁ specified by the scale signal. A plurality of pitch converting devices for performing such pitch conversion are provided, and these are controlled by a plurality of scale signals.

<Effect> As described above, according to the present invention, the pitch of the input audio frequency signal can be changed to a plurality of signals each having a pitch designated by a plurality of scale signals. Therefore, for example, when a person's singing voice is input as an input audible frequency signal, a plurality of scale signals is generated by an input means such as a keyboard, and the keyboard is played, audible frequency signals of a plurality of pitches designated by the keyboard are generated. The obtained sound effect is similar to that of a chorus, and can be made to be a chorus with the singing voice of the original person.

<Embodiment> FIG. 1 is a block diagram for explaining the operation of the basic blocks constituting the present invention. In the figure, 12 is a microphone that picks up voice and outputs an audible frequency signal. This audio frequency signal is supplied to the pitch conversion device 14. The pitch conversion device 14 is of a reference to the same pitch conversion device described above constituting the fourth figure, according to the pitch conversion amount P, and determines a write clock signal f _o, the read clock signal f _v , The pitch of the input audio frequency signal is changed. In this embodiment, since the audio frequency signal based on the voice is input, the upper limit frequency is about 10 KHz. Thus, the write clock signal f _o
Should be 20 KHz or more according to the sampling theorem. Read clock signal f _v and write clock signal f _o
As described above, since there is a relation of f _v = Pf _o , the master clock signal is divided by the programmable frequency divider that can change the division ratio by the pitch conversion amount P, and the read clock signal f are getting _v .

The audible frequency signal from the microphone 12 is also supplied to the pitch detection circuit 16 to detect the pitch f _{2 and} output pitch data representing the detected pitch. As the pitch detection circuit 16, for example, the one disclosed in JP-A-60-175099 can be used.

The pitch data detected by this pitch detection circuit 16 is
It is supplied to the control circuit 18. The control circuit 18 has a scale signal source 20.
The scale signal is also supplied from. As the scale signal source 20, a keyboard capable of outputting a scale signal by a performance operation or a sequencer capable of outputting a scale signal as automatic performance data can be used. Further, as the scale signal, an audio frequency signal having a pitch f ₁ is not used, but when a certain key is pressed, the number corresponding to the key and the speed at which the key is pressed are digital signals. It is possible to use a signal representing a musical scale, such as a digital signal representing the number corresponding to the depressed key of the MIDI signal transmitted in. The control circuit 18 determines the pitch conversion amount P based on the scale signal and the pitch detected by the pitch detection circuit 16. For example, when the pitch f ₂ detected by the pitch detection circuit 16 is 330 Hz and the pitch f ₁ represented by the scale signal output from the scale signal source 20 is 440 Hz, the pitch conversion amount is 440/330. When the scale signal is supplied by the MIDI signal as described above, it is necessary to convert the key number of the MIDI signal into a frequency corresponding to this. A lookup table (not shown) is used for this conversion.

The pitch conversion amount P is supplied to the pitch conversion device 14. In the pitch converter 14, the frequency is f ₀ * P (= f ₀ * 440/330) by dividing the master clock.
To generate the read clock signal f _v . As a result, the pitch of the audio frequency signal output from the pitch conversion device 14 is Has been changed to the pitch specified by the scale signal. The audio signal whose pitch has been changed is amplified by the amplifier 22 and supplied to the speaker (not shown).

An embodiment of the present invention is shown in FIG. In this embodiment, n pitch conversion devices are provided. When the control circuit 18 receives a plurality of scale signals from the scale signal source 20, the control circuit 18 determines each pitch conversion amount P _{1 to} P _n based on the pitch detected by the pitch detection circuit 16 and each scale signal. , Pitch converters 14-1 to 14-n, respectively. Therefore, one audio frequency signal can be simultaneously converted into audio frequency signals of different pitches and output,
If you generate multiple appropriate scale signals from the scale signal source 20,
The same acoustic effect as chorus can be obtained.

Another embodiment of the present invention is shown in FIG. This pitch conversion device also converts one audio frequency signal into audio frequency signals of different pitches at the same time and outputs the same, but the circuit configuration is simplified as compared with the embodiment of FIG. That is, the second embodiment requires a plurality of pitch conversion devices 14-1 to 14-n, which complicates the circuit configuration. Therefore, in the pitch conversion device of FIG. 3, only one pitch conversion device 14 is provided and the read clock signals are f _{v1 to} f _vn.
As described above, a plurality of digital signals are generated and the digital signals are read out from the memory 6 in a time division manner so that one pitch conversion device 14 functions as a plurality of pitch conversion means. Of course, the read clock signals f _{v1 to} f _vn are generated by the control circuit 18 based on the pitch conversion amounts P _{1 to} P _1n . The read digital signal is latched by a corresponding one of the n latch circuits and then converted into an audio frequency signal through a digital / analog converter and a low-pass filter connected to each latch circuit. Is output.

In each of the above embodiments, the voice is converted into an audio frequency signal by the microphone 12 and supplied to the pitch conversion device and the pitch detection circuit.However, a so-called pickup is provided in the body of the natural musical instrument, whereby the audio frequency signal is supplied. It may be generated and supplied to the pitch conversion device and the pitch detection circuit. In each of the above embodiments, the digital memory is used as the memory of the pitch conversion device, but an analog memory may be used. Further, in each of the above-described embodiments, the pitch conversion is performed by the method of changing the frequency ratio of the clock at the time of writing and the clock at the time of reading (variable sampling method). A changing method (fixed sampling method) can also be used.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining the operation of basic blocks constituting the present invention, FIG. 2 is a block diagram of one embodiment of the present invention, and FIG. 3 is a block showing another embodiment of a pitch conversion device. FIG. 4 and FIG. 4 are block diagrams showing an example of the pitch conversion device used in the embodiment of the present invention. 14, 14-1 to 14-n ... pitch conversion device, 16 ... pitch detection circuit, 18 ... control circuit, 20 ... scale signal source.

Claims (4)

(57) [Claims] 1. A pitch detecting means for detecting a pitch of an audio frequency signal, a means for inputting a plurality of different scale signals, and a pitch detected by the pitch detecting means and a plurality of the input scale signals, respectively. Control means for determining a plurality of pitch conversion amounts on the basis of a plurality of pitches corresponding to, and a plurality of pitch conversion means for converting the pitch of the audio frequency signal according to the plurality of pitch conversion amounts. Chorus effect device. 2. A chorus effect device according to claim 1, wherein the plurality of different scale signals are inputted from a keyboard for performing a performance operation. 3. The chorus effect device according to claim 1, wherein the plurality of different scale signals are input from a sequencer. 4. The chorus device according to claim 1, wherein the plurality of pitch conversion means are realized by operating one pitch conversion device in a time division manner.