Signal processing device, signal processing method, program, and rangehood apparatus

A signal processing method to be used in a signal processing device which is to be combined with a sound input/output device,

• the sound input/output device including a first sound input device disposed in a target space in which noise generated from a noise source propagates, the first sound input device being configured to collect the noise, a sound output device configured to receive a cancellation signal to output a cancelling sound for cancelling the noise to the target space, and a second sound input device configured to collect a resultant sound of the noise and the cancelling sound in the target space,
• the signal processing method comprising:
• outputting the cancellation signal from a sound cancelling filter in which a filter coefficient is set, the cancellation signal being based on an output of the first sound input device;
• calculating a first filter coefficient by a coefficient calculator based on an output of the first sound input device and an output of the second sound input device;
• and
• calculating a second filter coefficient by applying, to the first filter coefficient, a window function for suppressing an oscillation of a noise cancellation characteristic by an oscillation suppressor to set the second filter coefficient as the filter coefficient of the sound cancelling filter,
• wherein
• the window function has a characteristic that a window function value decreases as time passes.

A signal processing device to be used in combination with a sound input/output device,

• the sound input/output device including a first sound input device disposed in a target space in which noise generated from a noise source propagates, the first sound input device being configured to collect the noise, a sound output device configured to receive a cancellation signal to output a cancelling sound for cancelling the noise to the target space, and a second sound input device configured to collect a resultant sound of the noise and the cancelling sound in the target space,
• the signal processing device comprising:
• a sound cancelling filter in which a filter coefficient is set, the sound cancelling filter being configured to output the cancellation signal based on an output of the first sound input device;
• a coefficient calculator configured to calculate a first filter coefficient based on the output of the first sound input device and an output of the second sound input device;
• and
• an oscillation suppressor configured to calculate a second filter coefficient by applying, to the first filter coefficient, a window function for suppressing an oscillation of a noise cancellation characteristic,
• wherein
• the oscillation suppressor is capable of switching between a first operation for setting the first filter coefficient as the filter coefficient of the sound cancelling filter and a second operation for setting the second filter coefficient as the filter coefficient of the sound cancelling filter,
• the signal processing device further includes an oscillation sensor configured to detect the oscillation of the noise cancellation characteristic, and
• the oscillation suppressor performs the first operation when the oscillation of the noise cancellation characteristic is not detected, whereas the oscillation suppressor performs the second operation when the oscillation of the noise cancellation characteristic is detected.