JPH0690633B2 - Audio noise generation circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to speech synthesis, and more particularly to an arithmetic process determined based on data read from a memory that stores waveform data sampled at predetermined time intervals. The present invention relates to a voice noise generating circuit of a voice synthesizer to be executed.

[Conventional technology]

Conventionally, in order to synthesize a voice, the data obtained by periodically sampling the original sound is stored in a memory, the arithmetic processing determined based on the data read from the memory is executed, and finally the D / A conversion is performed. There is a method of synthesizing analog signals with a container.

[Problems to be solved by the invention]

In the conventional voice synthesis method described above, since voice noise has a higher frequency than the tone waveform, if the noise waveform is to be sampled as it is, the sampling interval must be shortened, which results in an enormous amount of sampling data and memory capacity. Since there is a limit to that, there is a drawback that the synthesis time of the voice becomes short.

Further, the voice noise has a feature that the frequency spectrum is a continuous spectrum having a peak at a specific frequency depending on the type of voice as shown in FIG. The peak frequency of this frequency spectrum is usually around 8 kHz for sub-voice noise and around 4 kHz for sub-voice noise. A circuit that can easily generate pseudo voice noise that can be synthesized with a counter frequency-divided signal of a circuit that is conventionally synchronized with clocks, while generating synthetic noise that has a spectrum peak at a specific frequency and becomes a continuous spectrum, Was not known.

[Means for solving problems]

An audio noise generation circuit of the present invention includes a memory in which a part of a waveform obtained by sampling an original sound of audio noise is stored, a binary counter for designating an address of the memory, and a vorinominal counter for setting an initial value in the binary counter. , A circuit for detecting a match by comparing the value of the binary counter and the value of the polynomial counter, and a DA converter for converting the output of the memory into an analog signal. An audio noise waveform with a spectrum peak at a specific frequency has waveforms with frequency components substantially corresponding to the peak frequency when viewed temporally, and frequency components higher and lower than the peak frequency are mixed. , Its amplitude is considerably smaller than that of the peak frequency component. When the waveform of the peak frequency component is repeated to synthesize the voice noise waveform having such characteristics, a single spectrum is obtained, and therefore waveforms of several waveforms are extracted from the original sound. If this is repeated as it is, a line spectrum having a frequency component of the peak frequency of the original sound is obtained, but it is not a continuous spectrum.
When repeating several waveforms extracted from the original sound, a continuous frequency spectrum is obtained by repeating the start position and end position of the waveform randomly. In the present invention, the polynomial counter is used to randomly set the start position and the end position. The period of the polynomial counter has practically no effect on the synthesized spectrum. In the present invention, the memory address is designated by the binary counter so that the noise waveform data extracted from the original sound is output after the start position is set. [Embodiment] Next, the present invention will be described with reference to the drawings. To do.

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention. Address input terminals 2 and 3 specify the upper address of memory 4,
The lower address of the memory 4 is designated by the binary counter 7. Four types of noise waveforms can be selected by switching the inputs of the address input terminals 2 and 3. As an example of the contents of the memory 4, as shown in FIG.
The data of 64 points sampled for each is stored. 40kHz to clock input terminal 1 of binary counter 7
The matching circuit 8 detects that the value of the binary counter 7 matches the value of the polynomial counter 9 by inputting the clock of, and when they match, the contents of the polynomial counter 9 are moved one by the matching output of the matching circuit 8. deep. At this time, the start address of the original sound noise sampling waveform stored in the memory 4 is input to the binary counter 7, and the value of the polynomial counter 9 becomes the end address. Matching circuit 8
Since the coincidence output of is not output, the binary counter 7 is 40kH
It counts up by +1 by the clock of z and becomes the address input of the memory 4, and the original sound noise sampling waveform inside the memory 4 appears as the output of the memory 4. When this operation is repeated and the output of the memory 4 is converted into an analog signal by the DA converter 5, a signal having a continuous frequency spectrum shown in FIG. 4 close to the frequency spectrum of the original sound noise shown in FIG. 3 is obtained at the output terminal 6. To be

〔The invention's effect〕

As described above, according to the present invention, a part of the data obtained by sampling the original sound waveform is extracted and the signal having a continuous frequency spectrum can be synthesized by repeating the data. In particular, since both the start position and end position of the sampling waveform are specified by the contents of the polynomial counter, it is possible to generate a signal with a continuous frequency spectrum with a more random waveform because there is no repetition of the same part in terms of time. . In the case of voice noise, the frequency at which the frequency spectrum becomes maximum is as high as 8 kHz, so sampling cannot be done well unless the sampling interval is less than 50 μs. However, because of this, the voice noise remains unchanged at 25 μs.
When sampling every, the sampling point in 1 second becomes 40,000 points and the memory needs 40,000 addresses,
According to the present invention, even if the composite data is output every 25 μs, the memory capacity is 64 addresses, and the effect of reducing the memory capacity is remarkable. In addition, noise having a different frequency spectrum can be synthesized by increasing the memory capacity as needed. Furthermore, since a signal with a continuous frequency spectrum can be configured with a simple circuit using a periodic clock, it is suitable for digital LSI, and since the data sampled from the noise waveform of the original sound is used, it has a frequency spectrum close to the original noise. Synthesized noise is obtained, and high-quality speech noise can be synthesized. The number of stages of the binary counter, the clock input frequency of the binary counter, the number of output bits of the memory, the number of bits of the DA converter, etc. are related to the sound quality of the synthetic noise, and it is obvious that an appropriate value may be selected.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, and FIG.
FIG. 3 is a data waveform diagram in which a noise waveform of an original sound to be stored in the memory 4 in the figure is sampled, FIG. 3 is a frequency spectrum diagram of original sound noise, and FIG. 4 is a frequency spectrum diagram of synthetic noise. 1 ... Clock input terminal, 2 ... Address input terminal, 3
...... Address input terminal, 4 ... Memory, 5 ... DA converter, 6 ... Output terminal, 7 ... Binary counter, 8 ...
Matching circuit, 9 ... Polynomial counter.

Claims (1)

[Claims] 1. A storage means for storing at least a part of a waveform obtained by sampling a noise original sound of voice, a binary counter for continuously generating addresses for reading the storage information from the storage means, and a polynomial counter. And, when the value of the binary counter and the value of the polynomial counter match, set the value of the polynomial counter to the binary counter as an initial value,
After that, the value of the binary counter is used as the address of the storage means, and the audio noise generation circuit is characterized.