Patent ID: 7949140

Claim:
A sound measuring apparatus for measuring a sound-arrival delay time from a speaker to a microphone on the basis of a result obtained by outputting a signal from the speaker and picking up the signal using the microphone, the sound measuring apparatus comprising: control means for performing control so that a test signal is expanded in a time axis to produce a time-expanded test signal, the time-expanded test signal being output from the speaker; and delay time measuring means for measuring an expansion-based delay time based on a time difference between the test signal and a signal obtained from the microphone representative of the time-expanded test signal and subsequently time compressed, and deriving the sound-arrival delay time from the time difference, wherein: the test signal comprises a time stretched pulse signal; the delay time measuring means obtains a downsampled time stretched pulse signal by downsampling the time-expanded test signal that is picked up by the microphone according to an expansion factor by which the time stretched pulse signal is expanded, and measures a first delay time on the basis of a time difference between an impulse response that is obtained from the downsampled time stretched pulse signal and an impulse signal that the test signal is based on; and the delay time measuring means multiplies the first delay time by the expansion factor to obtain the sound-arrival delay time as the expansion-based delay time.