Tsuyoshi Mekata

Apparatus and method for speech signal processing

In an apparatus for speech signal processing, first a coefficient calculation is performed to determine a value for suppressing a change of level of an input signal. Next, an input signal delay is performed to delay the input signal by a time required for the coefficient calculation. Then an output of the input signal delay is multiplied by the value obtained by the coefficient calculation, thereby obtaining an output signal.

Speech signal processing apparatus for amplifying an input signal based upon consonant features of the signal

An apparatus for processing a speech signal includes a coefficient calculating circuit for receiving an input signal, and for generating a first value for suppressing a change of level of the input signal; a first delay circuit for receiving the input signal, and for delaying the input signal by a predetermined time; a feature extracting circuit for receiving the input signal, and for deriving a feature value representing a feature of consonants from the input signal; a coefficient control circuit for receiving the first value from the coefficient calculating circuit and the feature value from the feature extracting circuit, and for changing the amplitude and the duration of the first value depending on the feature value, so as to generate a second value; a multiplying circuit for receiving the delayed input signal from the first delay circuit and the second value from the coefficient control circuit, and for multiplying the delayed input signal by the second value.

Noise suppressing apparatus and its adjusting apparatus

The adjustment of a noise suppressing apparatus inputs the voice signal with the noises being piled up in it to decide the weight coefficient of the neutral network 130 with a back propagating method so that the errors of the output signal and of the noiseless signal may become minimum, the noise suppressing apparatus where noises in a voice signal are suppressed even in a situation where the positional relation between the noise source and the voice source may often change, and noises offensive to the voice after the noise suppression may not remain, the suppressing effect is not deteriorated even if the time pattern of the input signal is varied.

Variable-speech-rate audiometry for hearing aid evaluation.

A new hearing aid evaluation method using variable-speech-rate audiometry (VSRA) was developed. VSRA was newly created based on the Japanese speech audiometry authorized by the Japan Audiological Society. The ordinary speech audiometry can not reveal a temporal factor in word discrimination ability of the hearing impaired. Since, with VSRA, we can compare several performance-intensity curves obtained from different speech-rate speech audiometries, the impact on the auditory system of each patient by the fast or slow speech rate could be easily determined. Taking the temporal factor of the auditory systems into consideration by using VSRA, hearing aid evaluation was performed for a master hearing aid with three types of signal processing and fitting for 36 hearing impaired subjects. Then hearing aid evaluation was performed using VSRA for a newly developed portable multi-function digital hearing aid with two types of signal processing and analog hearing aids which had been used by hearing-impaired patients. As a result, VSRA was useful for hearing aid evaluation, in particular, for cases when ordinary normal speech rate audiometry does not provide a significant difference in word discrimination scores. In addition, using VSRA revealed that amplitude compression is more effective for improvement of word discrimination than linear amplification.