Data processing: speech signal processing – linguistics – language – Speech signal processing – Recognition
Reexamination Certificate
2000-04-20
2004-05-04
Dorvil, Richemond (Department: 2654)
Data processing: speech signal processing, linguistics, language
Speech signal processing
Recognition
C704S226000, C704S223000
Reexamination Certificate
active
06732075
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sound synthesizing apparatus and method, adapted to synthesize at a receiving side a wide-band signal from an input narrow-band sound signal or its parameters transmitted by a communications system or a broadcasting system, for example. The present invention also relates to a telephone apparatus adopting the sound synthesizing apparatus and method, and a program service medium by which the sound synthesizing method is served as a program.
2. Description of the Related Art
The sound quality of the conventional wire telephone and radio telephone has not satisfied the telephone users. One of the reasons for such a low sound quality lies in the fact that the frequency band of the current telephony is limited to a range of 300 to 3,400 Hz.
Since the transmission path for use in the telephony is limited by the relevant rules and standards, it is difficult to widen the frequency band. For a higher sound quality in the field of the telephony, various methods have been proposed to predict at the receiving side an out-of-band component of a received sound and generate a wider-band signal.
Typically, there has been proposed a method in which based on the well-known method for linear predictive coding (LPC) analysis and synthesis, used in the sound signal processing, both a linear predictive factor &agr; acquired from a narrow-band sound signal and a linear prediction residual or an excitation source acquired by quantizing the residual are band-widened and a wide-band sound is synthesized by the LPC from the band-widened linear predictive factor &agr; and excitation source.
However, since the wide-band sound thus acquired is distorted, the frequency component of the original sound is filtered out of the synthesized wide-band sound and it is added to the original sound.
There has also been proposed an excitation source frequency band widening method in which taking in consideration the fact that an excitation source is a nearly white noise, a zero is inserted between two successive samples to generate an aliasing component and this component is taken as a wide-band excitation source.
When one zero is inserted between two successive samples, for example, the spectrum will appear symmetrical with respect to the Nyquist frequency taken as a line. Therefore, this method will be somehow effective for acquiring a wide-band excitation source from a narrow-band excitation source which is originally a nearly white noise.
On the assumption that the sampling frequency of a narrow-band signal is 8 kHz, that of a wide-band signal is 16 kHz and a narrow-band excitation source is limited to 300 to 3,400 Hz, for example, the wide-band excitation source acquired by the above-mentioned method will be of 300 to 3,400 Hz and 4,600 to 7,700 Hz with a gap between 3,400 and 4,600 Hz. Thus, the frequency band corresponding to this gap will not be generated even by the wide-band LPC synthesis but a wide-band sound not containing a frequency band corresponding to the gap will be generated. Thus, the wide-band sound is not any natural sound.
As in the above, since the excitation source resulted from the LPC synthesis including the band widening, etc. is low in quality, the synthesized signal will also have a low quality.
OBJECT AND SUMMARY OF THE INVENTION
It is therefore an object of the present invention to overcome the above-mentioned drawbacks of the prior art by providing a sound synthesizing apparatus and method capable of synthesizing a quality wide-band signal through improvement of the quality of the excitation source.
It is another object of the present invention to provide a telephone apparatus having a receiving means capable of providing a quality wide-band signal by adopting the above sound synthesizing apparatus and method.
It is further object of the present invention to provide a program service medium serving the sound synthesizing method in the form of a program and thus capable of providing a quality wide-band signal inexpensively.
According to the present invention, there is provided a sound synthesizing apparatus for synthesizing a wide-band signal from a part of an output signal acquired by a filtering synthesis whose input parameter is a linear prediction residual or excitation source of a narrow-band signal, the apparatus including means for adding a noise signal to the linear prediction residual or excitation source.
According to the present invention, there is also provided a sound synthesizing apparatus for synthesizing a wide-band signal from a part of an output signal acquired by a filtering synthesis whose input parameter is a linear prediction residual or excitation source of a narrow-band signal, the apparatus including means for generating a wide-band excitation source from the linear prediction residual or excitation source and means for adding a noise signal to the wide-band excitation source.
According to the present invention, there is also provided a sound synthesizing apparatus for synthesizing a wide-band signal from a part of an output signal acquired by a filtering synthesis whose input parameter is a linear prediction residual or excitation source of a narrow-band signal, the apparatus including means for adding a noise signal to the linear prediction residual or excitation source and means for generating a wide-band excitation source from the linear prediction residual or excitation source to which the noise signal has been added by the noise adding means.
According to the present invention, there is also provided a sound synthesizing apparatus for synthesizing a wide-band signal from a part of an output signal acquired by a filtering synthesis whose input parameter is a linear prediction residual or excitation source of a narrow-band signal, the apparatus including means for analyzing the narrow-band signal to provide a linear prediction residual signal, means for generating a wide-band residual signal from the linear prediction residual acquired by means of the analyzing means, and means for adding to the wide-band residual signal a noise signal having a signal component whose frequency is not included in the frequency band of the wide-band residual signal generated by the wide-band residual signal generating means.
According to the present invention, there is also provided a sound synthesizing apparatus for synthesizing a wide-band signal from a part of an output signal acquired by a filtering synthesis whose input parameter is a linear prediction residual or excitation source of a narrow-band signal, the apparatus including means for analyzing the narrow-band signal to provide a linear prediction residual signal; means for adding to the linear prediction residual signal a noise signal having a signal component whose frequency is not included in the frequency band of the linear prediction residual signal generated by the analyzing means; and means for generating a wide-band residual signal from the linear prediction residual signal to which the noise signal has been added by the noise adding means.
According to the present invention, there is also provided a sound synthesizing method for synthesizing a wide-band signal from a part of an output signal acquired by a filtering synthesis whose input parameter is a linear prediction residual or excitation source of a narrow-band signal, the method including a step of adding a noise signal to the linear prediction residual or excitation source.
According to the present invention, there is also provided a sound synthesizing method for synthesizing a wide-band signal from a part of an output signal acquired by a filtering synthesis whose input parameter is a linear prediction residual or excitation source of a narrow-band signal, the method including steps of generating a wide-band excitation source from the linear prediction residual or excitation source and adding a noise signal to the wide-band excitation source.
According to the present invention, there is also provided a sound synthesizing method for synthesizing a wide-band signal f
Nishiguchi Masayuki
Omori Shiro
Dorvil Richemond
Maioli Jay H.
Patel Kinari
Sony Corporation
LandOfFree
Sound synthesizing apparatus and method, telephone... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sound synthesizing apparatus and method, telephone..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sound synthesizing apparatus and method, telephone... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3197885