A sound collecting apparatus, comprising: a plurality of microphones that collects a first sound from outside the sound collecting apparatus and a second sound from a noise source in the sound collecting apparatus, each of the plurality of microphones outputting a microphone signal; and at least one processor that is adapted, in operation, to perform operations including: dividing, on a one-to-one basis with the plurality of microphones, the microphone signal output by each of the plurality of microphones into signals in mutually different frequency bands; calculating, on a one-to-one basis with the dividing of the microphone signal output by each of the plurality of microphones, a signal level for each of the mutually different frequency bands; calculating correlation values between the plurality of microphones for each group of identical frequency bands according to the signal level calculated for each of the mutually different frequency bands; and deciding whether at least one of the plurality of microphones is sound-insulated, according to the correlation values; characterized in that the microphone signal is divided into signals in predetermined frequency bands, and when one of the correlation values only in a predetermined one of the predetermined frequency bands exceeds a threshold value, the plurality of microphones is decided to be not sound-insulated. a plurality of microphones that collects a first sound from outside the sound collecting apparatus and a second sound from a noise source in the sound collecting apparatus, each of the plurality of microphones outputting a microphone signal; and at least one processor that is adapted, in operation, to perform operations including: dividing, on a one-to-one basis with the plurality of microphones, the microphone signal output by each of the plurality of microphones into signals in mutually different frequency bands; calculating, on a one-to-one basis with the dividing of the microphone signal output by each of the plurality of microphones, a signal level for each of the mutually different frequency bands; calculating correlation values between the plurality of microphones for each group of identical frequency bands according to the signal level calculated for each of the mutually different frequency bands; and deciding whether at least one of the plurality of microphones is sound-insulated, according to the correlation values; dividing, on a one-to-one basis with the plurality of microphones, the microphone signal output by each of the plurality of microphones into signals in mutually different frequency bands; calculating, on a one-to-one basis with the dividing of the microphone signal output by each of the plurality of microphones, a signal level for each of the mutually different frequency bands; calculating correlation values between the plurality of microphones for each group of identical frequency bands according to the signal level calculated for each of the mutually different frequency bands; and deciding whether at least one of the plurality of microphones is sound-insulated, according to the correlation values; characterized in that the microphone signal is divided into signals in predetermined frequency bands, and when one of the correlation values only in a predetermined one of the predetermined frequency bands exceeds a threshold value, the plurality of microphones is decided to be not sound-insulated.