EP0496829B1 - Auf dem lpc-verfahren beruhende sprachsynthese mit adaptivem pitchvorfilter - Google Patents
Auf dem lpc-verfahren beruhende sprachsynthese mit adaptivem pitchvorfilter Download PDFInfo
- Publication number
- EP0496829B1 EP0496829B1 EP90916987A EP90916987A EP0496829B1 EP 0496829 B1 EP0496829 B1 EP 0496829B1 EP 90916987 A EP90916987 A EP 90916987A EP 90916987 A EP90916987 A EP 90916987A EP 0496829 B1 EP0496829 B1 EP 0496829B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- signal
- pitch
- excitation signal
- filter
- speech
- 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 - Lifetime
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 claims description 9
- 238000011045 prefiltration Methods 0.000 title description 3
- 230000005284 excitation Effects 0.000 claims abstract description 36
- 238000000034 method Methods 0.000 claims description 10
- 238000001914 filtration Methods 0.000 claims description 7
- 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
- 235000003332 Ilex aquifolium Nutrition 0.000 description 1
- 241000209027 Ilex aquifolium Species 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Images
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
Definitions
- This invention relates generally to speech synthesis, and more particularly to linear predictive coding based speech synthesis.
- 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) 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 its 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).
- 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.
- EP 0294020 describes a vector adaptive coding method for speech and audio, while the article by Holm entitled “Automatic generation of mixed excitation in linear predictive speech synthesizer", and published in International Conference on Acoustics Speech and Signal Processing, vol.1, 30 March 1981, Atlanta, USA, pages 118-120, describes the addition of the fricative excitation model to the LPC synthesis model to improve the quality of speech reproduction.
- a method of synthesizing speech comprising: A) providing an excitation signal that includes pitch information that has been inserted by a pitch filter; further characterized by the steps of: B) filtering the excitation signal in an adaptive pitch enhancement filter to provide a pitch filtered excitation signal; C) filtering the pitch filtered excitation signal in a LPC speech synthesis filter to provide a synthesized speech signal.
- a receiving coded information signal may be used to provide the excitation signal.
- 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, which pitch information has been inserted by a pitch filter, in response to the coded information signal; wherein the radio is further characterized by: C) adaptive pitch enhancement filter means operably coupled to the excitation source means for filtering the excitation signal to provide a pitch filtered excitation signal; D) LPC filter means for receiving the pitch filtered excitation signal and for providing a synthesized speech signal in response thereto.
- 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.
- 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 synthesized speech signal in accordance with the coded information.
- 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).
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)
- Stereophonic System (AREA)
- Filters That Use Time-Delay Elements (AREA)
- Reduction Or Emphasis Of Bandwidth Of Signals (AREA)
- Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)
Claims (3)
- Verfahren zur Sprachsynthese, umfassend:a) Bereitstellung eines Erregersignals, das eine Tonhöheninformation enthält, die durch einen Pitchfilter (Tonhöhenfilter) eingefügt worden ist; weiterhin durch die folgenden Schritte gekennzeichnet:b) Filterung des Erregersignals in einem adaptiven Pitchanreicherungsfilter, um ein pitchgefiltertes Erregersignal bereitzustellen;c) Filterung des pitchgefilterten Erregersignals in einem LPC-Sprachsynthesefilter, um ein synthetisiertes Sprachsignal bereitzustellen.
- Verfahren nach Anspruch 1, das weiterhin den Schritt des Empfangens eines kodierten Informationssignals enthält, und wobei das kodierte Informationssignal genutzt wird, um ein Erregersignal bereitzustellen.
- Funkgerät, umfassend:(a) Funkfrequenzmittel zum Empfangen eines Rundfunksignals und zur Wiedergewinnung eines darin enthaltenen kodierten Informationssignals;(b) Erregerquellenmittel, das betriebsbereit mit dem Funkfrequenzmittel gekoppelt ist, zur Bereitstellung eines Erregersignals, das eine Tonhöheninformation enthält, und diese Tonhöheninformation durch einen Pitchfilter in Reaktion auf das kodierte Informationssignal eingefügt worden ist; und wobei das Funkgerät weiterhin gekennzeichnet ist durch:(c) adaptive Pitchanreicherungsfiltermittel, die betriebsbereit mit dem Erregerquellenmittel zur Filterung des Erregersignal verbunden sind, um ein pitchgefiltertes Erregersignal bereitzustellen;(d) LPC-Filtermittel zum Empfangen des pitchgefilterten Erregersignals und zur Bereitstellung eines synthetisierten Sprachsignals, in Reaktion darauf.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US42287189A | 1989-10-17 | 1989-10-17 | |
US422871 | 1989-10-17 | ||
PCT/US1990/005191 WO1991006091A1 (en) | 1989-10-17 | 1990-09-17 | Lpc based speech synthesis with adaptive pitch prefilter |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0496829A1 EP0496829A1 (de) | 1992-08-05 |
EP0496829A4 EP0496829A4 (en) | 1993-08-18 |
EP0496829B1 true EP0496829B1 (de) | 2000-12-06 |
Family
ID=23676771
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP90916987A Expired - Lifetime EP0496829B1 (de) | 1989-10-17 | 1990-09-17 | Auf dem lpc-verfahren beruhende sprachsynthese mit adaptivem pitchvorfilter |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0496829B1 (de) |
CN (1) | CN1051100A (de) |
AU (1) | AU644119B2 (de) |
CA (1) | CA2066568A1 (de) |
DE (1) | DE69033672T2 (de) |
WO (1) | WO1991006091A1 (de) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3328080B2 (ja) * | 1994-11-22 | 2002-09-24 | 沖電気工業株式会社 | コード励振線形予測復号器 |
GB9512284D0 (en) * | 1995-06-16 | 1995-08-16 | Nokia Mobile Phones Ltd | Speech Synthesiser |
DE19629946A1 (de) * | 1996-07-25 | 1998-01-29 | Joachim Dipl Ing Mersdorf | Ein LPC-basiertes Verfahren zur Analyse und Synthese von Sprachgrundfrequenzverläufen mittels Filterparametrisierung und Restsignalapproximation |
Family Cites Families (2)
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 |
US4969192A (en) * | 1987-04-06 | 1990-11-06 | Voicecraft, Inc. | Vector adaptive predictive coder for speech and audio |
-
1990
- 1990-09-17 EP EP90916987A patent/EP0496829B1/de not_active Expired - Lifetime
- 1990-09-17 AU AU67256/90A patent/AU644119B2/en not_active Expired
- 1990-09-17 WO PCT/US1990/005191 patent/WO1991006091A1/en active IP Right Grant
- 1990-09-17 DE DE69033672T patent/DE69033672T2/de not_active Expired - Lifetime
- 1990-09-17 CA CA 2066568 patent/CA2066568A1/en not_active Abandoned
- 1990-10-15 CN CN 90108434 patent/CN1051100A/zh active Pending
Also Published As
Publication number | Publication date |
---|---|
AU6725690A (en) | 1991-05-16 |
CN1051100A (zh) | 1991-05-01 |
DE69033672T2 (de) | 2001-05-10 |
EP0496829A1 (de) | 1992-08-05 |
EP0496829A4 (en) | 1993-08-18 |
AU644119B2 (en) | 1993-12-02 |
CA2066568A1 (en) | 1991-04-18 |
DE69033672D1 (de) | 2001-01-11 |
WO1991006091A1 (en) | 1991-05-02 |
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