Integrated speech synthesis circuit with internal and external excitation capabilities

• US 4,319,083 A
• Filed: 02/04/1980
• Issued: 03/09/1982
• Est. Priority Date: 02/04/1980
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Henderson, Alva E., Wiggins, Richard H.
• Primary Examiner(s): Nusbaum, Mark E.
• Application Number:
  US06/118,255
• Time in Patent Office: 764 Days
• Field of Search: 179/1 SA, 179/1 SM, 179/1 SC, 179/15.55 R, 179/15.55 T, 364/710, 364/724
• US Class Current: 704/264
• CPC Class Codes: G09B 19/06 Foreign languages with audible presentation of material to be studied G09B5/04
• CPC Class Codes: G10L 13/04 Details of speech synthesis systems, e.g. synthesiser structure or memory management

Abstract

A speech synthesis circuit implementable in an integrated circuit device, capable of converting frames of data into analog signals representative of human speech. The frames of data are comprised of digital representations of values of pitch, energy and certain filter coefficients, which are stored in non-volatile memory. The filter coefficients are utilized to control a linear predictive filter which is excited by voiced and unvoiced excitations stored in non-volatile memory. A control circuit coupling the excitation signals to the linear predictive filter allows the operator to select an external excitation signal rather than precalculated stored excitation signals. Thus, the synthesizer may be utilized in a vocoder application, wherein a residual excitation signal transmitted from an analysis circuit may be utilized as the excitation signal.

Claims

1. A speech synthesis system comprising:

voiced/unvoiced speech excitation means for generating voiced/unvoiced excitation speech signals;

external voiced/unvoiced speech excitation input means for receiving externally generated voiced/unvoiced excitation speech signals;

filter means for selectively converting excitation speech signals into digital speech signals representative of human speech;

control means electrically coupling said voiced/unvoiced speech excitation means to said filter means;

said external voiced/unvoiced speech excitation input means being directly electrically coupled to said filter means;

control signal input means operatively associated with said control means for receiving an external control signal;

said control means being deactivated in response to reception of the external control signal by said control signal input means and communication thereof to said control means for electrically uncoupling said voiced/unvoiced speech excitation means from said filter means;

said external voiced/unvoiced speech excitation input means being adapted to be used for providing external voiced/unvoiced excitation speech signals to said filter means during the time period when said voiced/unvoiced speech excitation means is electrically uncoupled from said filter means;

digital-to-analog converter means coupled to said filter means for converting said digital speech signals representative of human speech into analog signals; and

audio means coupled to said digital-to-analog converter means for converting said analog signals into audible sounds.

3. The speech synthesis system according to either of claims 1 or 2, wherein said filter means comprises a linear predictive filter.

4. The speech synthesis system according to either of claims 1 or 2, wherein said control means comprises a tri-state buffer.

5. The speech synthesis system according to either of claims 1 or 2, wherein said audio means comprises a speaker.

6. The speech synthesis system according to either of claims 1 or 2, wherein said externally generated voiced/unvoiced excitation speech signals comprise residual excitation signals.

2. A speech synthesis system comprising:

first memory means for storing a plurality of digital speech values including digital speech values representative of digital filter coefficients;

controller means operatively associated with said first memory means for accessing selected portions of said plurality of digital speech values including said digital speech values representative of digital filter coefficients in said first memory means;

digital filter speech synthesis means coupled to said controller means comprising;

second memory means for storing digital data including voiced and unvoiced excitation speech signals,

voiced/unvoiced speech excitation means operatively associated with said second memory means for selectively generating voiced and unvoiced excitation speech signals as stored in said second memory means,

digital filter means for selectively converting said voiced and unvoiced speech excitation signals and said accessed digital speech values representative of digital filter coefficients into digital speech signals representative of human speech, and

digital-to-analog converter means connected to the output of said digital filter means for converting said digital speech signals representative of human speech into analog signals;

audio means coupled to said digital-to-analog converter means for converting said analog signals into audible sounds;

a separate external voiced/unvoiced speech excitation input means distinct from said digital filter speech synthesis means for receiving externally generated voiced/unvoiced excitation speech signals;

control means electrically coupling said second memory means from which said voiced and unvoiced excitation speech signals are generated within said digital filter speech synthesis means to said digital filter means;

said external voiced/unvoiced speech excitation input means being electrically coupled to said digital filter means independently of said control means;

control signal input means operatively associated with said control means for receiving an external control signal;

said control means being deactivated in response to reception of the external control signal by said control signal input means and communication thereof to said control means for electrically uncoupling said second memory means from said digital filter means; and

said external voiced/unvoiced speech excitation input means being adapted to be used for providing external voiced/unvoiced excitation speech signals to said digital filter means during the time period when said memory means is electrically uncoupled from said digital filter means.