Method and means for creating prosody in speech regeneration for laryngectomees

Abstract

A device and a method to be used by laryngeally impaired people to improve the naturalness of their speech. An artificial sound creating mechanism which forms a simulated glottal pulse in the vocal tract is utilized. An artificial glottal pulse is compared with the natural spectrum and an inverse filter is generated to provide an output signal which would better reproduce natural sound. A digital signal processor introduces a variation of pitch based on an algorithm developed for this purpose; i.e. creating prosody. The algorithm uses primarily the relative amplitude of the speech signal and the rise and fall rates of the amplitude as a basis for setting the frequency of the speech. The invention also clarifies speech of laryngectomees by sensing the presence of consonants in the speech and appropriately amplifying them with respect to the vowel sounds.

Description

REFERENCE TO PRIOR APPLICATIONS [0001] This application is a continuation of application Ser. No. 09 / 641,157 filed Aug. 17, 2000, being U.S. Pat. No. 6,795,807 issued Sep. 21, 2004 which in turn claimed the benefit of the filing date of the applicant's provisional patent application No. 60 / 149,106 filed Aug. 17,1999.REFERENCE TO COMPUTER PROGRAM LISTING ON COMPACT DISC [0002] Included with this application is a compact disc named application Ser. No. 09 / 641,157 Baraff which contains five separate files, together which comprise table 1 referenced in this specification. The file names, date of creation on compact disc and file sizes are as follows: [0003] Main program file application Ser. No. 09 / 641,157 Baraff.txt, created Sep. 12, 2004 of size 27.0 KB; [0004] Pitch program file application Ser. No. 09 / 641,157 Baraff.txt, created Sep. 12, 2004 of size 4.09 KB; [0005] Synth program file application Ser. No. 09 / 641,157 Baraff.txt, created Sep. 12, 2004 of size 5.46 KB; [0006] LPC progr...

AI Technical Summary

Benefits of technology

[0018] In addition to providing prosody, the disclosed system has other capabilities providing increased naturalness including: noise cancellation of sound from a neck vibrator excitation source, feedback control to allow use of a microphone distant from the mouth, aspiration noise to mimic real speech, amplification selectively of consonants over vowels to assist in intelligibility, automatic gain control to allow for movement of the head with respect to the microphone, user selection of mood of speech, volume control, whisper speech, telephone mode, training aids, ability to interface with myoelectric signals to provide automatic hands free starting and stopping control as well as user controlled intonation, and the extraction of voice parameters from a user before laryngeal impairment to recreate the voice.

[0020] It is, therefore, the primary objective of the present invention is to provide intelligible and natural sounding speech for individuals with laryngeal impairment while including the feature of prosody as they speak. Accordingly, it is an object of this invention to recreate natural prosody without the conscious intervention of the user through use of a computer algorithm to process speech. It is also an object of the disclosed invention to provide for prosody and speech improvement by tapping the nerve signal generated in the larynx nerve which controls the larynx in normal speakers to that a signal can be provided for stopping and starting speech. It is also the object of the invention to utilize the same signal to provide information as to the larynx tension, which relates to the pitch of speech, such that the speaker's intent can be realized by utilization of the myoelectric signal to process speech.

Problems solved by technology

No speech devices to date have been able to capture, in sufficient detail, information about the specific speaker to recreate his / her own voice.

All of these devices have the drawback of sounding very mechanical.

Even when a user has manually changed the pitch, the sound has not been close to the natural sound of the human being.

There are a number of reasons that laryngectomees have not been able to use previous devices to their fullest potential.

Firstly, even with devices which have built in pitch control, it is extremely difficult to coordinate the fingers to imitate natural speech prosody.

Secondly, some of the subtleties of creating true prosody may occur in time scales faster than could be manually controlled.

These schemes using a programmed template would not be useful in a real time creation of speech for the laryngectomee because they require the understanding of the word and context to be applied.

Clearly techniques which are based on understanding the word before applying prosody will not be useful to solve this problem.

In practice, very few laryngectomees use this capability because the timing and control is too difficult.

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