Patent No. 4821326 Non-audible speech generation method and apparatus

 

Patent No. 4821326  Non-audible speech generation method and apparatus (MacLeod, Apr 11, 1989)

Abstract

A non-audible speech generation apparatus and method for producing non-audible speech signals which includes an ultrasonic transducer or vibrator for projecting a series of glottal shaped ultrasonic pulses to the vocal track of a speaker. The glottal pulses, in the approximate frequency spectrum extending from fifteen kilohertz to one hundred five kilohertz, contain harmonics of approximately 30 times the frequency of the acoustical harmonics generated by the vocal cords, but which may nevertheless be amplitude modulated to produce non-audible speech by the speaker's silently mouthing of words. The ultrasonic speech is then received by an ultrasonic detector disposed outside of the speaker's mouth and electrically communicated to a translation device which down converts the ultrasonic signals to corresponding signals in the audible frequency range and synthesizes the signals into artificial speech.

Notes:

SUMMARY OF THE PRESENT INVENTION

It is therefore an object of the present invention to provide a non-audible artificial speech generation device.

Another object of the present invention is to provide a non-audible artificial speech generation device which allows a speaker to produce the artificial speech by simply talking, but without use of the vocal cords or use of unvoiced speech (whispering).

Another object of the present invention is to provide a non-audible artificial speech generation device which projects ultrasonic pulses to the vocal tract of a speaker from a ultrasonic transducer or by direct contact with the throat of the speaker.

A further object of the present invention is to provide a non-audible artificial speech generation device which projects ultrasonic pulses shaped like the glottal pulses which are produced by the larynx during the natural production of speech.

A still further object of the present invention is to provide a non-audible artificial speech generation device which uses a vocoder operating at ultrasonic frequency levels to translate and synthesize the non-audible artificial speech produced by a speaker into the audible range.

A still further object of the present invention is to provide a method for producing an artificial speech communication signal which can be used to operate a variety of devices.

Briefly, a preferred embodiment of the present invention comprises an ultrasonic transducer or vibrator for projecting a series of glottal shaped ultrasonic pulses to the vocal track of a speaker. The glottal pulses, in the approximate frequency spectrum extending from fifteen kilohertz to one hundred five kilohertz, contain harmonics of approximately 30 times the frequency of the acoustical harmonics generated by the vocal cords, but which may nevertheless be amplitude modulated to produce non-audible speech by the speaker's silently mouthing of words. The ultrasonic speech is then received by an ultrasonic detector disposed outside of the speaker's mouth and electrically communicated to a translation device which down converts the ultrasonic signals to corresponding signals in the audible frequency range and synthesizes the signals into artificial speech.

These and other objects of the present invention will no doubt become apparent to those skilled in the art after having read the following detail disclosure of the preferred embodiment which is illustrated in the several figures of the drawing.
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Although the present invention has been described above in terms of a preferred embodiment, it is contemplated that numerous alterations and modifications of the invention will be apparent to those skilled in the art after having read the above disclosure. It is therefore intended that the following claims be interpreted as covering all such modifications and alterations as fall within the true spirit and scope of the invention.