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 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 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.