JPH0690077B2 - Pitch extractor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pitch extraction device for audio signals such as various musical sounds and voices.

2. Description of the Related Art In recent years, various pitch extraction technologies have been proposed with the progress of digital technology, and there are technologies for obtaining the autocorrelation of time waveforms and cepstrum technology, but the aim was to reduce the amount of calculation or to perform high-speed processing. Pitch extraction technology by polarity inversion detection is considered as a technology.

Hereinafter, the pitch extraction device described above will be described with reference to the drawings.

FIG. 3 shows the structure of a conventional pitch extracting device.

In FIG. 3, 9 is an acoustic signal input terminal, 10 is a high-pass filter, 11 is a low-pass filter, 12 is an A / D converter for converting an analog acoustic signal into digital data, and 13 is A.
/ D converter 12 detects the polarity inversion of the digital data output polarity inversion detection unit that outputs a polarity inversion detection signal, 14 is a polarity inversion detection signal output from the polarity inversion detection unit 13 A control unit that outputs a time measurement instruction signal that instructs start or end, 15 is a time measurement unit that measures the pitch period of digital data according to the time measurement instruction signal, and 16 is an output terminal.

The operation of the pitch extracting device configured as described above will be described below.

The acoustic signal input from the microphone or the like to the acoustic signal input terminal 9 is subjected to antialiasing filtering satisfying the sampling theorem by passing through the lowpass filter 11 after the direct current component is removed by the highpass filter 10 and A / The D converter 12 sequentially performs analog-to-digital conversion to obtain digital data.

Next, the polarity inversion detection unit 13 detects the polarity inversion of the digital data sequentially output from the A / D converter 12, and then outputs the polarity inversion detection signal to the control unit 14. The control unit 14 outputs to the timing unit 15 a timing instruction signal for instructing the start or end of the timing of the pitch period according to the polarity inversion detection signal. When the control unit 14 outputs a timing instruction signal for instructing to start timing, the timing unit 15 starts counting the number of samples of digital data, that is, timing the pitch period.

Further, when the control section 14 outputs a time measurement instruction signal for instructing the end of time measurement, the time measurement section 15 outputs the number of samples up to that time, that is, the time measurement result to the control section 14 as a pitch cycle, and then resets the time measurement result. By repeating the above operation according to the polarity inversion detection signal of the polarity inversion detection unit 13, the pitch cycle of the digital data sequentially output from the A / D converter 12 is obtained.

In order to convert the Ni pitch periods into a so-called pitch Fi [Hz], it is possible to obtain Fi [Hz] = Fs / Ni (1) by using the sampling frequency Fs [Hz].

However, in the above-mentioned configuration, as is clear from the equation (1), not only the accuracy of the pitch period obtained by the sampling frequency is changed, but also the sampling frequency is increased in order to improve the accuracy. Therefore, there is a problem that an expensive device is required because a high-speed arithmetic processing is required.

In view of the above problems, the present invention provides a pitch extraction device that does not require high-speed arithmetic processing and has a simple structure and high accuracy.

Means for Solving the Problem In order to achieve this object, a pitch extraction device of the present invention is a binarizing means for binarizing an audio signal, and a cycle of a voice signal binarized by the binarizing means. A time measuring means for measuring the time, a memory means for sequentially storing the time measured values measured by the time measuring means, and a memory means capable of storing at least two or more time measured values, and a time measured value and a memory means clocked by the time measuring means. Comparing the stored time values sequentially, comparing means for outputting a coincidence signal when the ratio of the two time values is within a predetermined value range, and the time value stored in the storage means compared by the comparison means, It is composed of adding means for performing cumulative addition, and is configured to obtain the cumulative addition result of the count value from the adding means by the coincidence signal from the comparing means.

Operation According to the present invention, the input acoustic signal is converted into a digital signal by the binarizing means and the period is timed by the timekeeping means. The measured value, which is the measured result, is stored in the storage means and is compared with the past measured result by the comparison means. If there is a result that is almost the same as the past time measurement result, the cumulative addition value of the past time measurement values that is the comparison target is the value corresponding to the pitch period of the input acoustic signal, and this is the value of the adder. It is latched by the output latch and is output.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a pitch extracting device according to an embodiment of the present invention, and FIG. 2 is operation waveforms of the block diagram shown in FIG.

In FIG. 1, 1 is an acoustic signal input terminal, 2 is a binarizing means for binarizing an acoustic signal, 3 is a timing controlled by the output of the binarizing means 2 and has an output latch (not shown) at the output. Means 4, memory means for storing the time value output from the time means 3, 5 compares the output of the time means 3 and the time value read from the memory means 4, the ratio of both time values is determined. When it is within the range, comparison means for outputting a coincidence signal, 6 is addition means with an output latch (not shown) for cumulatively adding the clock values read from the storage means 4, 7 is a clock signal generation means, and 8 is an output terminal. is there.

When the acoustic signal shown in FIG. 2 (a) is input to the acoustic signal input terminal 1, the output signal of the binarizing means 2 has the waveform shown in FIG. 2 (b). The clocking means 3 is a clock signal generating means 7
Clocking is performed by the clock signal supplied from, and the timing value Tn, which is the timing result, is latched in the output latch at the rising edge of the waveform of the output signal of the binarizing means 2, and the timing result is reset and the timing of the next cycle is started. . FIG. 2 (c) shows the signal of the output latch of the timing means 3. The storage means 4 stores the time count value Tn at the rising edge of the waveform of the output signal of the binarization means 2, and then sequentially reads the past time count values from the time count value Tn _-1 as shown in FIG. 2 (d). This past time value Tn _-1 ,, Tn _-2
...... Tn _- m is sequentially compared with the time value Tn by the comparison means 5, and when the ratio of both time values is within the predetermined range, the second value
The coincidence signal shown in FIG. 7E is output, and the storage means 4 stops reading the measured value. The addition means 6, as shown in FIG. 2 (f), the past time measurement value Tn _-1 read out from the storage means 4, Tn _-2 ...... Tn _- a m cumulatively added, comparing means 5
The cumulative addition result is latched in the output latch by the output of the coincidence signal. The output signal of the output latch of the adding means 6 is shown in FIG.

The output P ₀ of the output latch of the adding means 6 is a signal corresponding to the pitch period of the acoustic signal, and has a relationship with the clock signal CK. Therefore, it is understood that if the pitch period is to be obtained with high accuracy, the frequency of the clock signal should be increased.

Further, from FIGS. 2 (a), (b), and (g), since the pitch period is T ₀ + T ₁ , T ₁ + T ₂ , T ₂ + T _3, ... It is possible to prevent erroneous extraction.

EFFECTS OF THE INVENTION According to the present invention, the input acoustic signal is converted into a digital signal by the binarizing means, and the period is clocked by the clocking means. The measured value, which is the measured result, is stored in the storage means and is compared with the past measured result by the comparison means. If there is a result that is almost the same as the past time measurement result, the cumulative addition value of the past time measurement values that is the comparison target is the value corresponding to the pitch period of the input acoustic signal, and this is the value of the adder. Since the data is latched and output by the output latch, it is possible to perform highly accurate pitch extraction with a simple configuration and prevent pitch extraction errors due to harmonics or noise of the acoustic signal.

Further, since it is not necessary to perform high-speed arithmetic processing in order to improve the pitch extraction accuracy, it can be realized by inexpensive hardware.

[Brief description of drawings]

FIG. 1 is a block diagram of a pitch extracting device according to an embodiment of the present invention, FIG. 2 is an exemplary waveform diagram of each data according to an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional pitch extracting device. Is. 1 ... Acoustic signal input terminal, 2 ... Binarizing means, 3 ... Time counting means, 4 ... Storage means, 5 ... Comparison means, 6 ... Addition means, 7 ... Clock signal generation means, 8 ... … Output terminals,
9: Acoustic signal input terminal, 10: High-pass filter, 11
…… Low-pass filter, 12 …… A / D converter, 13 ……
Polarity reversal detector, 14 ... Control, 15 ... Timer, 16 ...
Output terminal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Daisuke Mori 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Masahiro Nakanishi 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A binarizing means for binarizing an acoustic signal, a clocking means for clocking a cycle of a voice signal binarized by the binarizing means, and a clocked value clocked by the clocking means. A storage means capable of sequentially storing and storing at least two or more time-measured values, sequentially compares the time-measured values measured by the time-measurement means with the time-measured values stored in the memory means, and compares the two time-measured values with each other. The comparison means includes a comparison means for outputting a coincidence signal when the ratio is within a predetermined value range, and an addition means for cumulatively adding the time count values stored in the storage means, which are compared by the comparison means. A pitch extracting apparatus, wherein the cumulative addition result of the count values is obtained from the adding means by the coincidence signal from the means.