Sound field measurement device

A sound field measurement device, comprising:

• a test sound source configured to generate a wide frequency range signal including an audio signal and a test signal;
• a plurality of speakers configured to reproduce the audio signal and the test signal included in the wide frequency range signal to output an audio sound and a test sound respectively;
• a plurality of microphones configured to detect the test sound when the test sound is outputted from one of said plurality of speakers;
• a measurement section configured to determine a number and positions of people present in a sound field, based on test sound detected by said plurality of microphones;
• and
• a directionality controller configured to change a directionality of said plurality of microphones toward a position of the one speaker, outputting the test sound, of the plurality of speakers, wherein
• the test sound source outputs at least a high frequency range signal included in a range from 1 kHz to 10 kHz where the presence or absence of people has a significant influence and a low frequency range signal included in a range from 80 Hz to 800 Hz where the presence or absence of people does not have a substantial influence in a time division manner or at least a wide frequency range signal which includes both the high frequency range signal and the low frequency range signal;
• and
• the measurement section includes:
• a frequency analyzer configured to analyze frequency characteristics of each of the test sound signals detected by the plurality of microphones;
• a high frequency range level calculator and a low frequency range level calculator configured to calculate a high frequency range signal level and a low frequency range signal level, respectively, of each of the test sound signals detected by the plurality of microphones based on the analysis by the frequency analyzer;
• a reference value storage section configured to store a reference value which is obtained by normalizing a level value in a predetermined portion of a high frequency range from the high frequency range level calculator in the absence of people in the sound field with a level value in a predetermined portion of a low frequency range from the low frequency range level calculator in the absence of people in the sound field;
• and
• the determination section configured to determine the number and positions of people present in the sound field by comparing a normalized value with the reference value stored in the reference value storage section, the normalized value being obtained by normalizing a level value in a predetermined portion of a high frequency range from the high frequency range level calculator with a level value in a predetermined portion of a low frequency range from the low frequency range level calculator.