Storage medium, microphone, and engine speed acquisition device

A tangible non-transitory computer-readable storage medium storing an active acoustic control program downloaded using a communication device that transmits and receives data to and from a server, the active acoustic control program causing an operation processing device to execute a control signal generation processing of generating a control signal that causes a speaker provided in a vehicle compartment of a vehicle to output a canceling sound in order to reduce noise in the vehicle compartment, the control signal generating processing comprising:

• generating a basic signal corresponding to the noise generated from a drive source;
• adaptively performing signal processing on the basic signal with an adaptive notch filter to generate the control signal;
• detecting through a microphone provided in the vehicle compartment cancellation error noise obtained by synthesizing the noise and the canceling sound output from the speaker based on the control signal;
• inputting an error signal corresponding to a cancellation error noise detected through the microphone;
• generating a reference signal by correcting the basic signal based on the correction value;
• and
• sequentially updating a filter coefficient of the adaptive notch filter based on the error signal and the reference signal in a manner that the error signal is minimized;
• and
• executing, before executing the control signal generation processing, an identification processing of identifying a transfer characteristic of the sound in a transfer path from the speaker to the microphone,
• wherein the identification processing comprising:
• generating, while the drive source is stopped, an identification signal corresponding to an identification sound having a predetermined frequency;
• adaptively performing signal processing on the identification signal with the adaptive notch filter to generate the control signal;
• detecting through the microphone the identification sound output from the speaker based on the identification signal, and inputting a noise signal corresponding to the identification sound detected through the microphone;
• generating a virtual error signal which is a difference between the noise signal and the control signal;
• and
• sequentially updating the filter coefficient of the adaptive notch filter based on the virtual error signal and the identification signal in a manner that the error signal is minimized, and using an updated filter coefficient as the correction value.