Patents Examined by R. Vass
  • Patent number: 4747132
    Abstract: A howling canceller includes a group of filters for dividing an output of a microphone into a plurality of frequency bands, a transfer characteristic estimation unit for estimating a transfer characteristic (i.e.-impulse response) of a low frequency range in an echo path extending from a loudspeaker to the microphone, an echo signal estimation unit for producing an approximate echo signal of the low frequency range proceeding from the loudspeaker to the microphone, a subtracter for subtracting an output of the echo signal estimation unit from an output of a low-pass filter of the filters, and an adder for adding an output of the subtracter to outputs of the filters other than the low-pass filter.
    Type: Grant
    Filed: April 3, 1985
    Date of Patent: May 24, 1988
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Satoru Ibaraki, Hiroki Furukawa, Hiroyuki Naono