公开(公告)号：US20230254640A1

公开(公告)日：2023-08-10

申请号：US18010842

申请日：2020-07-09

Applicant: TOA Corporation

Inventor： Toshimitsu SUETSUGU

IPC: H04R3/02 ,  H04R3/04 ,  H04R27/00

CPC classification number: H04R3/02 ,  H04R3/04 ,  H04R27/00 ,  H04R2227/007

Abstract: An object is to provide a public address device that effectively prevents occurrence of howling without a drop of the gain. A public address device 100 includes: a loudspeaker 1 that generates a reproduced sound on the basis of a loudspeaker driving signal u(n); a microphone 2 that collects the reproduced sound and an input sound v(n) to generate a microphone-collected-sound signal y(n); a first filter 301 that generates, on the basis of the loudspeaker driving signal u(n), a pseudo echo signal e(n); an echo-cancelling unit 302 that obtains a difference between the microphone-collected-sound signal y(n) and the pseudo echo signal e(n) to generate an echo-cancelled signal d(n); a second filter 311 that whitens the input sound v(n) included in the loudspeaker driving signal u(n); a third filter 312 that whitens the input sound v(n) included in the microphone-collected-sound signal y(n); a first adaptive filter 313 that uses, as a reference signal, an output signal output from the second filter 311, and uses, as a desired signal, an output signal output from the third filter 311, and estimates a propagation characteristic Wo from the loudspeaker 1 to the microphone 2; a unit that repeatedly updates a filter coefficient W of the first filter 301 on the basis of a filter coefficient W identified by the first adaptive filter 313; and a frequency shifting unit 32 that performs a frequency shift on the echo-cancelled signal d(n) to generate the loudspeaker driving signal u(n).