Abstract:
A device 1 for measuring a propagation time of a sound wave comprises a sound source means 11 and a calculation means 12 . The sound source means 11 outputs a time stretched pulse as a sound source signal input to a speaker 3 . The calculation means 12 calculates a cross-correlation function of the time stretched pulse and the sound signal which is output from the speaker 3 and is received in a microphone 4 . Based on the cross-correlation function, the propagation time of the sound wave between the speaker 3 and the microphone 4 is found.
Abstract:
A device 1 for measuring a propagation time of a sound wave comprises a sound source means 11 and a calculation means 12 . The sound source means 11 outputs a time stretched pulse as a sound source signal input to a speaker 3 . The calculation means 12 calculates a cross-correlation function of the time stretched pulse and the sound signal which is output from the speaker 3 and is received in a microphone 4 . Based on the cross-correlation function, the propagation time of the sound wave between the speaker 3 and the microphone 4 is found.
Abstract:
Resonant frequencies f2 and f3 detected in a resonant space are determined as center frequencies of a dip. Based on measurement values at a speaker and a microphone in the resonant space, a basic amplitude frequency characteristic Ca and a target amplitude frequency characteristic Cd are found. A smoothness degree on a frequency axis is larger in the target amplitude frequency characteristic Cd than the basic amplitude frequency characteristic Ca. A damping level and quality factor of the dip are determined based on a difference between the basic amplitude frequency characteristic Ca and the target amplitude frequency characteristic Cd in the center frequencies f2 and f3 of the dip and frequencies near the center frequencies.
Abstract:
A howling margin measuring device (20), comprising a treatment means (28) having a gain regulating means (21) and a compressor (22) connected in series to each other and a control means (23). The gain regulating means (21) gives a gain to an inputted voice signal and outputs that signal, and the compressor (22) compresses the voice signal at a specified ratio when the level of the inputted voice signal is equal to or higher than a threshold level and outputs that signal. The control means (23) can control the gain of the gain regulating means (21), and can read the compression level of the compressor (22). The control means (23) reads the compression level of the compressor (22) while gradually increasing the gain of the gain regulating means (21) and, based on whether the read compression level is above a specified value or not, determines whether howling occurs or not. Then, based on the gain of the gain regulating means (21) obtained when the control means (23) determines that howling occurs, the control means (23) calculates howling margin.
Abstract:
Resonance frequencies f2, f3 detected in a resonance space are decided to be dip center frequencies. According to the measurement values obtained in a loudspeaker and a microphone in the resonance space, a basic amplitude frequency characteristic Ca and a target amplitude frequency characteristic Cd are obtained. The target amplitude frequency characteristic Cd has a greater smoothness than the basic amplitude frequency characteristic Ca on the frequency axis. The dip attenuation level and sharpness are decided according to the difference between the basic amplitude frequency characteristic Ca and the target amplitude frequency characteristic Cd at the dip center frequencies f2, f3 and in the vicinity thereof.
Abstract:
A resonance frequency sensor (20) comprises sound source means (21), signal combining switch means (26, 27) and measuring means (25). The signal combining switch means (26, 27) switch between a first status of outputting a measurement signal and a second status of outputting a synthetic signal generated by combining the measurement signal and the output signal from a microphone (14). The sensor (20) determines the resonance frequency on the basis of comparison between a first amplitude frequency characteristic measured in the first output status and a second amplitude frequency characteristic measured by the second output status.
Abstract:
The resonance frequency of a magnified-sound space is determined based on a basic amplitude/frequency characteristic obtained by sound magnifying, from a speaker (13) located in the magnified-sound space (40), a predetermined measurement signal and then receiving the sound by use of a microphone (14) located in the magnified-sound space (40); also based on a first amplitude/frequency characteristic obtained by sound magnifying, from the speaker (13), the measurement signal and a first delayed signal, which is obtained by delaying an output signal from the microphone (14) by a first delay time of zero or more, and then receiving the sound by use of the microphone (14); further based on a second amplitude/frequency characteristic obtained by sound magnifying, from the speaker (13), the measurement signal and a second delayed signal, which is obtained by delaying an output signal from the microphone (14) by a second delay time of zero or more, and then receiving the sound by use of the microphone (14). The second delay time is different in value from the first delay time.
Abstract:
A sound wave propagation time measurement device (1) includes sound source means (11) and calculation means (12). The sound source means (11) outputs a time stretching pulse as a sound source signal to be input to a loudspeaker (3). The calculation means (12) calculates a correlation function correlating the time stretching pulse with a sound reception signal from a microphone (4) which has received the output sound from the loudspeaker (3). According to this correlation function, the sound wave propagation time between the loudspeaker (3) and the microphone (4) is calculated.