Patent Application
20080082327
a) is a graph showing intelligibility defmed with respect to frequency under the condition that VCV syllabic sound including a preceding vowel /a/, and being divided at each frequency into two sound sections to be heard by respectively ears.
The following description will be directed to a hearing aid method of allowing a hearing-impaired person to hear a sound with improved intelligibility by dividing the sound into two sections to be respectively outputted to his/her ears. It is well known that the hearing-impaired person feels that a sound is improved in intelligibility by hearing, by respective ears, two sections into which the sound is divided. However, nobody has known how to divide the sound into two sections.
The inventers have conducted experiments on whether or not the hearing-impaired person feels that the sound is improved in intelligibility by hearing, by respective ears, two sound sections into which the sound is divided with on the basis of vowel-consonant-vowel (VCV) syllabic sound.
As a result, the inventers have found that the sound is improved in intelligibility under the condition that the sound is divided into two sound sections at a frequency determined on the basis of the type of preceding vowel.
In this experiment, the sound is divided into two sound sections corresponding to respective ears. One of the sound sections includes low frequency components processed in lowpass filter (LPF), while the other of the sound sections includes high frequency components processed in highpass filter (HPF).
The vowel-consonant-vowel (VCV) syllabic sounds include respective preceding vowels /a/ and /u/, and is divided at a frequency defined at the vicinity of formant frequency.
The transverse axis indicates “frequency” at which the sound is divided into two sound sections, while the vertical axis indicates “intelligibility” with which the hearing-impaired person hears the sound.
As shown in
From the above-mentioned experiments, the inventers have found that syllabic sound just after each vowel is improved in intelligibility by reason that the syllabic sound is divided, at a frequency to be appropriately determined on the basis of the features of the inputted sound signal, into two sound sections to be respectively outputted to ears.
More specifically, the method can allow hearing-impaired person to hear a sound with improved intelligibility, in comparison with a condition that the inputted signal is divided at a fixed frequency into two sound sections, by reason that the inputted sound signal is divided into two sound sections at a frequency which is changed on the basis of the features of the inputted sound signal.
While there has been described in the foregoing description about the fact that the inputted sound signal is divided on the basis of the type of vowel, cutoff frequencies of bandpass filters may be changed on the basis of the combination of continuous syllabic sounds.
The first and second embodiments of the sound processing apparatus according to the present invention will be described hereinafter with reference to accompanying drawings.
As shown in
In the sound processing apparatus thus constructed, the analog sound signal from the sound input means 11 is converted into a digital sound signal by the A/D converter 12, while the digital sound signal is outputted to the lowpass filter 13, the highpass filter 14, and the analyzing means 15.
The analyzing means 15 analyzes the input signal, and to detect a frequency band corresponding to a masking component and a frequency band corresponding to a masked component to be masked by the masking component, and changes the cutoff frequencies of the lowpass and highpass filters 13 and 14 on the basis of the analysis of the input signal to ensure that the masking component is included in the sound to be outputted by one of the first and second sound output means 18 and 19, and the masked component is included in the sound to be outputted by the other of the first and second sound output means 18 and 19.
The analyzing means 15 detects the type of each vowel on the basis of the analysis of the input signal. When the preceding vowel is identified as /a/, the analyzing means 15 sets a cutoff frequency “f2” shown in
The analyzing means 15 may be adapted to identify the type of the preceding vowel by detecting first and second formant frequencies.
The analyzing means 15 may be adapted to detect a first formant frequency, to change the cutoff frequencies of the lowpass and highpass filters 13 and 14 on the basis of the first formant frequency, and to allow one of the lowpass and highpass filters 13 and 14 to output a component corresponding to the first formant frequency, and to allow the other of the lowpass and highpass. filters 13 and 14 to cut off or attenuate the component corresponding to the first formant frequency.
The lowpass filter 13 outputs frequency components included in frequency bands smaller than the cutoff frequency set by the analyzing means 15, while the highpass filter 14 outputs frequency components included in frequency bands larger than the cutoff frequency set by the analyzing means 15.
The digital signals from the highpass and lowpass filters 13 and 14 are respectively converted into analog signals by the first and second D/A converters 16 and 17, while the analog signals are respectively converted by the first and second sound output means 18 and 19 into sounds to be outputted to user's right and left ears.
From the foregoing description, it will be understood that the sound processing apparatus according to the first embodiment of the present invention can allow a user to hear a sound with improved intelligibility by reason that the analyzing means 15 is adapted to analyze an input signal, to change the cutoff frequencies of the lowpass and highpass filters 13 and 14 on the basis of the analysis of the input signal to ensure that the masking component is included in the sound to be outputted by one of the first and second sound output means 18 and 19, and the masked component is included in the sound to be outputted by the other of the first and second sound output means 18 and 19.
In this embodiment, the sound processing apparatus is adapted to divide the input signal into two sound signals corresponding to right and left ears, one of the sound signals including high frequency components of the input signal, the other of the sound signals including low frequency components of the input signal. However, the sound processing apparatus may be adapted to output a band-limited sound to one of the right and left ears, and to output a sound to the other of the right and left ears without bandwidth constraint. The sound processing apparatus may be adapted to divide the input signal into two or more sound signals.
As shown in
In this case, the analyzing means 22 is adapted to analyze the input signal, and to control the first and second switches 23 and 24 to ensure that the all-pass filters 20 and 21 receives the digital sound signal from the A/D converter 12 when the judgment is made that the sound is sufficiently clear or does not include a voice component, and outputs the digital sound signals to the D/A converters 16 and 17 through the first and second adders 25 and 26, without limiting, in frequency range, the digital sound signals.
From the foregoing description, it will be understood that the sound processing apparatus thus constructed according to the present invention can allow a user to hear a sound by both ears, without changing the sound into two sound sections, when the inputted sound is sufficiently clear or identified as a sound other than a voice.
As shown in
The analyzing means 15 may be adapted to have the highpass and lowpass filters 13 and 14 function as all-pass filters by changing the filter coefficients of the highpass and lowpass filters 13 and 14.
In this embodiment, the first sound output means 18 is adapted to receive a sound signal from the lowpass filter 13, while the second sound output means 19 is adapted to receive a sound signal from the highpass filter 14. However, the sound processing apparatus may comprise amplifying means for amplifying the sound signals from the highpass and lowpass filters 13 and 14, and outputting the amplified sound signals to the first and second sound outputting means 18 and 19.
The sound processing apparatus according to the second embodiment of the present invention comprises first and second amplifying means 31 and 32 for amplifying, in each frequency band, the right and left channel signals on the basis of gains set in each frequency band, and rate-of-loudness-compensation calculating means 33 for analyzing, in power of each frequency band, the input signal, and adjusting, in each frequency band, the gains of the first and second amplifying means 31 and 32 on the basis of the power of each frequency band.
In the sound processing apparatus thus constructed as previously mentioned, the analog sound signal inputted into the sound input means 11 is converted by the A/D converter 12 to a digital sound signal to be outputted to the lowpass filter 13, the highpass filter 14, the analyzing means 15, and the rate-of-loudness-compensation calculating means 33.
As has been mentioned in the first embodiment, the analyzing means 15 is adapted to analyze the input signal from the sound input means 11, and to adjust cutoff frequencies of the lowpass and highpass filters 13 and 14 on the basis of the analysis of the analyzing means 15.
The rate-of-loudness-compensation calculating means 33 is adapted to analyze, in each frequency band, the energy of the input signal from the sound input means 11, to calculate, in each frequency band, gains of the first and second amplifying means 31 and 32 on the basis of user's right and left auditory properties deteriorated in dynamic range, and to set the calculated gains to the first and second amplifying means 31 and 32 to ensure that the user hears right and left channel sounds amplified appropriately in each frequency band on the basis of the calculated gains.
As shown in, for example,
The digital sound signals outputted by the first and second amplifying means 31 and 32 are respectively converted into analog sound signals by the first and second D/A converters 16 and 17, while the analog sound signals are respectively outputted by the first and second sound output means 18 and 19.
From the foregoing description, it will be understood that the sound processing apparatus according to the second embodiment of the present invention can improve, in intelligibility, a sound to be heard by the hearing-impaired person by reason that the rate-of-loudness-compensation calculating means 33 is adapted to analyze, in power of each frequency range, the sound signal inputted into the sound input means 11, and to adjust, in each frequency range, the gains of the first and second amplifying means 31 and 32 on the basis of his/her auditory property.
As shown in
In this case, the analyzing means 34 is adapted to analyze, in each frequency range, the sound signal inputted into the sound input means 11, to adjust, in each frequency range, the gains of the first amplifying means 35 on the basis of the analysis of the sound signal to ensure that the first amplifying means 35 has the digital sound signal passed therethrough in low frequency range smaller than a cutoff frequency, and to adjust, in each frequency range, the gains of the second amplifying means 36 on the basis of the analysis of the sound signal to ensure that the second amplifying means 35 has the digital sound signal passed therethrough in high frequency range larger than the cutoff frequency.
In each embodiment, the sound processing apparatus is adapted to change, on the basis of the analysis of the input signal, the input signal into two sound signal sections corresponding to user's right and left ears. However, the sound processing apparatus may have two sound signals inputted therein, and may be adapted to process two input signals on the basis of the changed frequency characteristics. Further, the sound processing apparatus may be adapted to divide the input signal into two or more sound signal sections.
As will be seen from the foregoing description, the sound processing apparatus according to the present invention has an advantageous effect of allowing a hearing- impaired person to hear a sound with improved intelligibility. The sound processing apparatus according to the present invention is useful as a hearing aid apparatus, an audio apparatus, a cellular phone, an apparatus for loudening a sound, an apparatus for performing voice communication, and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-272159 | Sep 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/16787 | 9/13/2005 | WO | 00 | 3/13/2007 |
