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(11) | EP 0 530 523 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Active silencer with improved method of selecting coefficient sequence |
| (57) There is the most appropriate coefficient sequence retained in a memory (15) in addition
to a coefficient sequence for silencing signal operation used in a digital signal
processor (14). Updating of coefficient sequences for operation, saving into the memory
(15), and loading of the coefficient sequence in the memory (15) into a memory for
operation of the digital signal processor (14) are performed according to variation
of average power of a silencing error signal e(n) in silencing operation. Furthermore,
with detection of abnormality of an input/output signal and a coefficient sequence,
the coefficient sequence retained in the memory (15) is loaded into the operating
memory (21) of the digital signal processor (14) to implement a stable control state,
and the sound input signal buffer (23) is cleared to cut a feedback loop in an instant
to prevent howling. |