Speech synthesizer

Details Speech synthesizer Speech synthesizer

1981-10-22

1985-01-01

Kemeny, E. S. Matt

Electrical audio signal processing systems and devices

Monitoring/measuring of audio devices

Loudspeaker operation

G10L 100

Patent

active

044919581

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to speech synthesizers and particularly to a speech synthesizer for synthesizing speech on the basis of a parameter signal indicative of the frequency spectrum envelope of a speech signal and information indicating the period of a speech signal.


BACKGROUND ART

In the information service network for offering information such as stock market conditions, weather forecasts, guidance on various exhibitions and so on in the form of speech, it is desired that different kinds of information are transmitted on a digital signal to the terminal equipment of the network, where the digital signal is converted to speech by a speech synthesizer. In a teaching machine, vending machine, anouncment apparatus for giving announcements at a meeting and so on where a small number of spoken words are used, a speech synthesizer can be used which employs a semiconductor memory instead of a magnetic recording tape which has been used to date.
In a digital speech synthesizer in which speech signals are converted to digital signals and then stored and the stored digital signals are combined in such a manner as to form speech, a continuous speech signal is chopped at constant time intervals and characteristic parameters of the speech are extracted from the chopped speech waveforms. These parameters are converted to digital signals and stored. The stored parameters are combined in such a manner as to form speech. Thus, a speech unit of the synthesized sound can be reduced to a monosyllable shorter than a word. This permits a number of words to be formed without increase of the memory capacity. In addition, such a speech synthesizer has no mechanically movable portions and therefore does not cause any trouble due to wear or the like so that the maintenance thereof is easy.
It is thus preferable that a speech synthesizer synthesizes speech on the basis of the characteristic parameters of speech for easy maintenance and small memory capacity.
Since the spectrum distribution of speech is changed by the natural movement of the voice modifying organs such as the tongue and the lips, the change of the spectrum distribution is gentle, and during a short period of time in the range of 10 to 3 m seconds it can be considered to be substantially stationary. Thus, the characteristics of the spectrum of speech are derived precisely from the spectrum of speech during this stationary period of time, thereby to enable the analysis of speech, and synthesis of speech on the basis of the extracted information. For analysis and synthesis of speech, it is necessary to derive from the speech spectrum during the short period of time in which the change of distribution of the speech spectrum can be considered to be stationary, a parameter indicative of the envelope of the spectrum, a parameter indicative of the amplitude of the speech signal, pitch information corresponding to the fundamental vibration frequency of the vocal chords, and discrimination information for indicating a voiced sound or an unvoiced sound.
One of the speech analysis and synthesis systems for the extraction of the characteristic parameters from speech signals, and for synthesizing the speech signals on the basis of the parameters is a PARCOR type method using PARCOR coefficients (partial auto-correlation coefficients) as a kind of a linear prediction coefficient.
The apparatus utilizing this method produces PARCOR coefficients as the characteristic parameters of speech signals. That is, a speech signal during a short period of time in which the change of the frequency spectrum of the speech signal is gentle and stationary is sampled at a sampling period of, for example, 8 kHz. The samples at two close points, of the successive samples are estimated by the least squares of the samples existing between those at the two points. The predicted values are compared with the actual sample values at the two points and then the correlation (PARCOR coefficients) among the resulting differences are determined. In the speech synthesizer, a signal generator

REFERENCES:
patent: B476577 (1976-01-01), Flanagan
patent: 4328395 (1982-05-01), Henderson

Affiliated with

Also associated with

Rating

Speech synthesizer does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Speech synthesizer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Speech synthesizer will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-580726