AU644119B2 - Lpc based speech synthesis with adaptive pitch prefilter - Google Patents
Lpc based speech synthesis with adaptive pitch prefilterInfo
- Publication number
- AU644119B2 AU644119B2 AU67256/90A AU6725690A AU644119B2 AU 644119 B2 AU644119 B2 AU 644119B2 AU 67256/90 A AU67256/90 A AU 67256/90A AU 6725690 A AU6725690 A AU 6725690A AU 644119 B2 AU644119 B2 AU 644119B2
- Authority
- AU
- Australia
- Prior art keywords
- signal
- pitch
- excitation signal
- speech
- excitation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000015572 biosynthetic process Effects 0.000 title claims description 10
- 238000003786 synthesis reaction Methods 0.000 title claims description 10
- 230000003044 adaptive effect Effects 0.000 title description 5
- 238000011045 prefiltration Methods 0.000 title description 4
- 230000005284 excitation Effects 0.000 claims description 24
- 238000000034 method Methods 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 6
- 230000002194 synthesizing effect Effects 0.000 claims description 3
- 230000006870 function Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000008447 perception Effects 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
- G10L19/04—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using predictive techniques
- G10L19/26—Pre-filtering or post-filtering
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Multimedia (AREA)
- Health & Medical Sciences (AREA)
- Audiology, Speech & Language Pathology (AREA)
- Human Computer Interaction (AREA)
- Computational Linguistics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Compression, Expansion, Code Conversion, And Decoders (AREA)
- Noise Elimination (AREA)
- Filters That Use Time-Delay Elements (AREA)
- Stereophonic System (AREA)
- Reduction Or Emphasis Of Bandwidth Of Signals (AREA)
- Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)
Description
LPC BASED SPEECH SYNTHESIS WITH ADAPTIVE PITCH
PREFILTER
Technical Field
This invention relates generally to speech synthesis, and more particularly to linear predictive coding based speech synthesis.
Background of the Invention
The synthesis of speech through use of a linear predictive coding (LPC) based platform is known in the art. A prior art radio that embodies such a platform is depicted generally in Fig. 1 by the reference numeral 100. The radio (100) receives a speech coded signal (101) through an appropriate energy transducer (102), such as an antenna. An RF unit (103) converts the received signal (101) to baseband and demodulates the signal to recover the speech coded information. A parameter decoder (105) develops control parameters for various subsequent processes from this information. An excitation source (104) as described above utilizes the parameters provided to it to create an excitation signal and then provides that excitation signal (which excitation signal includes pitch information that has been inserted by a pitch filter) to an LPC filter (106)
which in turn provides, at it's output, a synthesized speech signal.
This synthesized speech signal is then filtered in an adaptive pitch postfilter (107) and an adaptive spectral postfilter (108), as well as a post emphasis filter (109), to enhance the perception of natural speech and to minimize the impact of various distortions and artifacts introduced in the synthesis process. The enhanced synthesized speech signal is then properly processed in an audio processing unit (111) and rendered audible through an appropriate audio transducer (112).
Each of the above generally referred to components is well known and understood in the art.
The pitch postfilter (107) serves an important function, in that it provides additional control of the pitch content of the synthesized speech. Without this filter, the resultant synthesized speech product may be rougher and of lower quality. Notwithstanding this important benefit, the pitch postfilter (107) frequently contributes artifacts to the resultant synthesized speech, which artifacts can themselves noticeably disturb the perception of natural speech. Accordingly, a need exists for providing appropriate pitch enhancement filtering in an LPC based speech synthesizing unit that minimizes a concurrent perceptible expression of artifacts in a resultant synthesized speech signal.
Summary of the Invention
This need and others are substantially met through provision of the LPC platform disclosed herein. According to the invention, the pitch enhancement
postfilter is moved from a position of processing the LPC filter output to a position where it processes the excitation input to the LPC filter. The subsequent processing of the LPC filter itself functions to minimize the perceptible effect of any artifacts introduced by the pitch enhancement prefilter in the resultant synthesized speech signal.
Brief Description of the Drawinos
Fig. 1 comprises a block diagram depiction of a prior art embodiment of a radio receiver having LPC based speech synthesis; and
Fig. 2 comprises a block diagram depiction of a radio having LPC 3asθd speech synthesis in accordance with the invention.
Best Mode For Carrying Out The Invention
In Fig. 2, a radio embodying the invention includes an antenna (102) for receiving a speech coded signal (101 ). An RF unit (103) processes the received signal to recover the speech coded information. This information is provided to a parameter decoder (105) that develops control parameters for various subsequent processes. An excitation source (104) as described above utilizes the parameters provided to it to create an excitation signal. This resultant excitation signal from the excitation source (104) is provided to a pitch prefilter (201) that functions to filter the pitch information contained in the excitation signal. The resultant filtered signal then passes to the LPC filter (106) which yields a
SUBSTITUTE SHEET
synthesized speech signal in accordance with the coded information.
Consistent with known methodology, this resultant signal is then further processed in an adaptive spectral postfilter (108) and post emphasis filter (109) to further enhance the quality of the synthesized speech, and is then processed in an audio processing unit (111 ) and rendered audible by an audio transducer (112).
What is claimed is:
SUBSTITUTE SHEET
Claims (3)
1. A method of synthesizing speech, comprising:
A) providing an excitation signal that includes pitch information; further characterized by the steps of:
B) filtering the excitation signal in a pitch enhancement filter to provide a pitch filtered " excitation signal;
C) filtering the pitch filtered excitation signal in a speech synthesis filter to provide a synthesized speech signal.
2. A method of synthesizing speech, comprising:
A) receiving a coded information signal;
B) using the coded information signal to provide an excitation signal that includes pitch information; further characterized by the steps of:
C) filtering the excitation signal in a pitch enhancement filter to provide a pitch filtered excitation signal;
D) filtering the pitch filtered excitation signal in a speech synthesis filter to provide a synthesized speech signal.
3. A radio, comprising:
A) RF means for receiving a broadcast signal and for recovering a coded information signal included therewith; B) excitation source means operably coupled to the
RF means for providing an excitation signal that includes pitch information in response to the coded information signal; wherein the radio is further characterized by: C) pitch enhancement filter means operably coupled to the excitation source means for filtering the pitch information in the excitation signal to provide a filtered excitation signal;
D) LPC filter means for receiving the filtered excitation signal and for providing a synthesized speech signal in response thereto.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US42287189A | 1989-10-17 | 1989-10-17 | |
US422871 | 1989-10-17 |
Publications (2)
Publication Number | Publication Date |
---|---|
AU6725690A AU6725690A (en) | 1991-05-16 |
AU644119B2 true AU644119B2 (en) | 1993-12-02 |
Family
ID=23676771
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU67256/90A Expired AU644119B2 (en) | 1989-10-17 | 1990-09-17 | Lpc based speech synthesis with adaptive pitch prefilter |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0496829B1 (en) |
CN (1) | CN1051100A (en) |
AU (1) | AU644119B2 (en) |
CA (1) | CA2066568A1 (en) |
DE (1) | DE69033672T2 (en) |
WO (1) | WO1991006091A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3328080B2 (en) * | 1994-11-22 | 2002-09-24 | 沖電気工業株式会社 | Code-excited linear predictive decoder |
GB9512284D0 (en) * | 1995-06-16 | 1995-08-16 | Nokia Mobile Phones Ltd | Speech Synthesiser |
DE19629946A1 (en) * | 1996-07-25 | 1998-01-29 | Joachim Dipl Ing Mersdorf | LPC analysis and synthesis method for basic frequency descriptive functions |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4969192A (en) * | 1987-04-06 | 1990-11-06 | Voicecraft, Inc. | Vector adaptive predictive coder for speech and audio |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4220819A (en) * | 1979-03-30 | 1980-09-02 | Bell Telephone Laboratories, Incorporated | Residual excited predictive speech coding system |
-
1990
- 1990-09-17 DE DE69033672T patent/DE69033672T2/en not_active Expired - Lifetime
- 1990-09-17 AU AU67256/90A patent/AU644119B2/en not_active Expired
- 1990-09-17 CA CA 2066568 patent/CA2066568A1/en not_active Abandoned
- 1990-09-17 EP EP90916987A patent/EP0496829B1/en not_active Expired - Lifetime
- 1990-09-17 WO PCT/US1990/005191 patent/WO1991006091A1/en active IP Right Grant
- 1990-10-15 CN CN 90108434 patent/CN1051100A/en active Pending
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4969192A (en) * | 1987-04-06 | 1990-11-06 | Voicecraft, Inc. | Vector adaptive predictive coder for speech and audio |
Also Published As
Publication number | Publication date |
---|---|
AU6725690A (en) | 1991-05-16 |
CN1051100A (en) | 1991-05-01 |
EP0496829B1 (en) | 2000-12-06 |
CA2066568A1 (en) | 1991-04-18 |
DE69033672D1 (en) | 2001-01-11 |
EP0496829A1 (en) | 1992-08-05 |
WO1991006091A1 (en) | 1991-05-02 |
DE69033672T2 (en) | 2001-05-10 |
EP0496829A4 (en) | 1993-08-18 |
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