Method and apparatus for synthesizing speech
First Claim
1. A speech synthesizing method including the steps of sectioning an input signal derived from a speech signal into frames and deriving a pitch for each sectioned frame, said method comprising the steps of:
- determining whether data for synthesizing speech of each frame contains a voiced sound or an unvoiced sound;
synthesizing a voiced sound with a fundamental wave of said pitch and its harmonic when the data of a frame is determined to contain a voiced sound; and
constantly initializing phases of said fundamental wave and its harmonic into a given value when the data of a frame is determined to contain an unvoiced sound.
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Abstract
A speech synthesizing method and apparatus arranged to use a sinusoidal waveform synthesis technique provide for preventing degradation of acoustic quality caused by the shift of the phase when synthesizing a sinusoidal waveform. A decoding unit decodes the data from an encoding side. The decoded data is transformed into the voiced/unvoiced data through a bad frame mask unit. Then, an unvoiced frame detecting circuit detects an unvoiced frame from the data. If there exist two or more continuous unvoiced frames, a voiced sound synthesizing unit initializes the phases of a fundamental wave and its harmonic into a given value such as 0 or π/2. This makes it possible to initialize the phase shift between the unvoiced and the voiced frames at a start point of the voiced frame, thereby preventing degradation of acoustic quality such as distortion of a synthesized sound caused by dephasing.
20 Citations
10 Claims
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1. A speech synthesizing method including the steps of sectioning an input signal derived from a speech signal into frames and deriving a pitch for each sectioned frame, said method comprising the steps of:
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determining whether data for synthesizing speech of each frame contains a voiced sound or an unvoiced sound; synthesizing a voiced sound with a fundamental wave of said pitch and its harmonic when the data of a frame is determined to contain a voiced sound; and constantly initializing phases of said fundamental wave and its harmonic into a given value when the data of a frame is determined to contain an unvoiced sound. - View Dependent Claims (2, 3, 4, 5)
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6. A speech synthesizing apparatus arranged to section an input signal derived from a speech signal into frames and to derive a pitch for each frame, comprising:
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means for determining whether data of each frame contains a voiced sound or an unvoiced sound; means for synthesizing a voiced sound with a fundamental wave of the pitch and its harmonic when the data of a frame is determined to contain a voiced sound; and means for initializing the phase of said fundamental wave and its harmonic to a given value when the data of the frame is determined to contain an unvoiced sound. - View Dependent Claims (7, 8, 9, 10)
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Specification