Patent ID: 7822496

Claim:
An audio signal processing method comprising the steps of: supplying an audio signal to each of a plurality of digital filters, the digital filters corresponding to respective amplitude characteristics; respectively supplying outputs from the plurality of digital filers to a plurality of speakers arranged in a speaker array to form a sound field; setting a delay time in each of the plurality of digital filters so that transmission delay times with which the audio signal arrives at a first point in the sound field via each of the plurality of digital filters and each of the plurality of speakers will coincide with each other; adjusting at least one amplitude characteristic of the plurality of digital filters such that the frequency response to the audio signal at a second point in the sound field is lower than the frequency response to the audio signal at the first point in the sound field, where the at least one amplitude characteristic is estimated by predicting a sample count of the signal at the second point and selecting effective ones of the amplitude characteristics corresponding to the sample count; and adjusting cut-off frequency of a variable high pass filter and the delay time in each of the digital filters based on the adjusted amplitude characteristics