JPS58201032A - pitch discrimination device - Google Patents

Abstract

PURPOSE:To discriminate an interval of a common pitch name in each octave, by fixing the center frequency of the 1st plural band filters individually corresponding to each octave on the frequency of the interval corresponding to each block filter in each octave. CONSTITUTION:Each octave is divided into twelve intervals in accordance with twelve temperament and a signl from an acoustic signal generating circuit 1 is applied to twelve block filters F1-F12 corresponding to respective intervals. Outputs from the block filters F1-F12 are individually inputted to an interval discriminating circuit 2, which compares effective values or peak values of the outputs from the filters F1-F12 mutually and detects a signal from the filter out of the filters F1-F12 from which the maximum level is obtained. On the basis of the input signals to the circuit 2, the circuit 2 discriminates the interval to which the acoustic signal belongs and the signal indicating the interval is outputted from the circuit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that discriminates whether a voice during singing or a sound from a musical instrument belongs to an interval common to each off-chord, regardless of the difference in octave.

The range of fundamental frequencies during singing ranges from about 80 Hz to 1000 H2, from the lowest note of bass to the highest note of soprano. Conventionally, for example, 40 to 50 independent filters each corresponding to an absolute pitch on the frequency axis are provided, outputs from these filters are compared, and the lowest frequency is detected to obtain the absolute pitch. According to such prior art,
The configuration is clearly complex. Furthermore, since pitches determined by such prior art are determined by absolute pitches corresponding to frequencies, pitches common to each octave interval, such as the German pitch name 0. Ols, D, Dis, lf[i, F', F'i
s.

Even if you want to know the names of a total of 12 notes (G, Gis, A, B, H), signals with the same note names that are more than an octave apart are derived individually, and the processing of those signals is complicated. An object of the present invention is to provide an interval discrimination system that can completely discriminate to which intervals each octave has a common pitch name, regardless of the value of the fundamental frequency of the acoustic signal to be discriminated. You can earn money by providing it.

FIG. 1 is a block diagram of the Issho side of the present invention.

The acoustic signal generation (b) path l may have a configuration that generates all the audio signals such as when singing, which is composed of a microphone and an amplifier circuit that amplifies all the signals from the microphone, or it may have a configuration in which all audio signals are generated, such as when singing, or a prerecorded audible signal. It may also be used for signals such as voices or musical performances that have a certain frequency. In this embodiment, the signal from the acoustic signal generating circuit 1 is discriminated to which pitch it belongs among pitches having a common pitch name in each of a plurality of (four in this embodiment) octaves. In this example, each octave is divided into 12 intervals according to 12 equal temperament. The signal from the acoustic signal generation circuit 1 is passed through 12 block filters Fl-, which individually correspond to each pitch.
Commonly given to F12.

Each block filter F1 to F12 has a similar configuration.

FIG. 2 is a block diagram showing a specific configuration of the block filter F1. Here, it is 1-1 to 12. Each block filter F1 is composed of four bandpass filters whose number is the same as the number of off-turfs.Fit~Fi4'! i: have. Here, for convenience of explanation, the center frequencies of these filters Fit to Fi4 are also determined by the reference row Fil-Fi4. The frequency F11 is a frequency corresponding to one pitch of the octave located in the low range of the signal from the acoustic signal generating circuit l. The frequencies Fi2 to F'14 are determined by the first to third equations.

Fi2=2・Fil...(1)
Fi3=4・Fil...(2)
Fi4=8・Fit...(3)
The center frequency F1j of the bandpass filter included in each of the block filters Fl-F12 is generally expressed by the fourth equation. Here, j is an arbitrary number of 1, 2, and 3.4.

F t j = p (1-x) j x 2 The wave number Fil is the lowest frequency of human vocalization to be discriminated among the 12 average pitches or the lowest frequency of sound generated by a musical instrument.

Figure 3 shows the pantone filter shown in Figure 2.
It is a graph showing the characteristics of l-Fi4. The center frequency of each bandpass filter Fil to Fi4 is indicated by the diameter reference Fil-Fi4 as described above, and the frequency width narrowed by 3 CIB from the output level at those center frequencies is l/12 octave, and the remaining frequency is It has the characteristic of attenuating with a steep slope in the range. The p-wave frequency bands of the bandpass filters l'1l-Fi4 in each of these block filters Fl to F12 are determined so that they do not include the frequency range of adjacent scales and have no overall characteristic or missing spectral components. (
The filters Fij differ only in center frequency, but have the same structure and characteristics such as response level.

The output from the block filter Fl-F12 is individually input to the pitch discrimination circuit 2. The pitch discrimination circuit 2 has a function of comparing the effective values or peak values of the outputs from the block filters Fl-F12 with each other and detecting the signal from the block filters Fl-F12 that provides the maximum level. Based on the signal inputted to the pitch discrimination circuit 2 in this way, it is discriminated to which pitch of the 12-tone scale the tone signal belongs, and this tone@zenclothes signal is the pitch discrimination circuit 2! 82.

In the above embodiment, the l octave is divided into 12 intervals in 12 equal temperament, but in other embodiments of the present invention, the octave may be divided into intervals other than the 12 scales, and the blocks are divided accordingly. The number and configuration of filters F1 to F12 are changed. An equalizer amplifier is interposed between the signal generation (b) path 1 and the block filter Fl-F12, and the level of the low-frequency component of the signal is completely improved to detect pitches in the low octave with high precision. It's okay. Further, the characteristics of the bandpass filter Fil-Fi4 included in each block filter F1 may be changed so that the characteristics are all different from those shown in FIG. The present invention can be used not only to discriminate all pitches of a voice during singing, but also to discriminate all pitches of a signal of a musical instrument such as a monomelody instrument.

As described above, according to the present invention, it is possible to completely discriminate whether or not the tone subtone to be discriminated belongs to the second plurality of pitches having the same pitch name common to the i6th octave with a relatively simple configuration. be able to be easily distinguished.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the Iksho side of the present invention, Figure 2 is a block diagram of the Bi
Specific structure of block filter F1 shown in the figure x
'iThe block diagram shown in Figure 3 is the bandpass filter Fi.
This is a graph showing all the characteristics of l-Fi4. l... Yours signal generation circuit, 2... Pitch discrimination circuit, F
l~F12. Fi...Block filter, Fil A
-Fi4...Bandpass filter agent Patent attorney Kei Nishi Department 111th

Claims (1)

[Claims] Each of the first plurality of octaves is divided into a second plurality of intervals common to each octave, and the acoustic signal is applied to a second plurality of block filters individually corresponding to each interval, each block filter individually corresponding to each interval. A first plurality of band-pass filters corresponding to A pitch discrimination device characterized in that each frequency is determined individually.