The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 25, 1997
Filed:
Sep. 24, 1996
Hisashi Sano, Wako, JP;
Shuichi Adachi, Utsunomiya, JP;
Honda Giken Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
A reproduced sound is sent from a speaker as a sound source unit provided in a sound field. An error signal is produced by a microphone on the basis of a difference in sound between the reproduced sound from the speaker and noise coming from the outside of the sound field into the sound field. A digital filter has a fixed transfer function approximated to a transfer function of the sound field, to which a signal for driving the speaker is supplied. Variation of the transfer function of the sound field is detected by the digital filter. A difference signal between the error signal and an output signal from the digital filter is calculated by an adder. The difference signal determined by the adder is inputted into an IMC filter. A signal for compensating the variation of the transfer function of the sound field and variation of the noise is produced by the IMC filter. A variable parameter of the IMC filter is set so that an absolute value of a product of a value of an approximated and set amount of variation, a distance from the sound source unit to the error-detecting unit, and the variable parameter of the IMC filter is less than 1. Thus, the noise coming into the inside of the sound field is canceled by using an output sound of the speaker.