Sound field measuring device, method, and program

A method for measuring a sound field using a sound field measuring device, comprising:

• an external output step in which an external output unit outputs a measurement signal composed of a periodic function having a code length of 2n−1 to a speaker so that the measurement signal is outputted from the speaker;
• a sound pick-up step in which the measurement signal outputted from the speaker in the external output step is picked up using a microphone;
• a Fourier transform step in which a Fourier transform unit obtains frequency characteristics by Fourier transforming measurement sound picked up using the microphone in the sound pick-up step with a sample length of 2m;
• a thinning-out step in which a thinning-out unit removes noise from the frequency characteristics obtained in the Fourier transform step by removing line spectra except for the (k×2m-n+1)th line spectra from the frequency characteristics;
• and
• an averaging step in which an averaging unit obtains averaged frequency characteristics of a sound field by calculating an average value of signal levels in a predetermined frequency range on the basis of frequency characteristics thinned out in the thinning-out step while shifting the frequency range in steps of a shorter frequency range than the frequency range, wherein
• n and m are each a natural number satisfying m>n, and
• k is k=0, 1, 2, and the like.

A sound field measuring program executed by a sound field measuring device for measuring frequency characteristics of a sound field using a measurement signal composed of a periodic function having a code length of 2n−1, the program causing a computer of the sound field measuring device to perform:

• an external output function of outputting a measurement signal composed of a periodic function having a code length of 2n−1 to a speaker so that the measurement signal is outputted from the speaker;
• a sound pick-up function of picking up the measurement signal outputted from the speaker by the external output function using a microphone;
• a Fourier transform function of obtaining frequency characteristics by Fourier transforming measurement sound picked up by the sound pick-up function with a sample length of 2m;
• a thinning-out function of removing noise from the frequency characteristics obtained by the Fourier transform function by removing line spectra except for the (k×2m-n+1)th line spectra from the frequency characteristics;
• and
• an averaging function of obtaining averaged frequency characteristics of a sound field by calculating an average value of signal levels in a predetermined frequency range on the basis of frequency characteristics thinned out by the thinning-out function while shifting the frequency range in steps of a shorter frequency range than the frequency range, wherein
• n and m are each a natural number satisfying m>n, and
• k is k=0, 1, 2, and the like.