| 摘要 |
In a listening device such as for example a hearing aid ( 1 ) where an input signal ( 10 ) is received by a microphone ( 2 ), converted from analog to digital ( 3 ), digitally processed ( 4 ) including a conversion from a time domain into a frequency domain, converted from digital to analog ( 5 ) and transmitted to a user by means of a loudspeaker ( 6 ), the internal digital processing ( 4 ) generates an unwanted noise signal, the so called undesired periodic noise ( 12 ), at specific frequencies. The undesired periodic noise is coupled via ground and the battery ( 7 ) into the signal processing path. According to the invention, the undesired periodic noise is filtered out of the input signal ( 10.2 ) during the digital signal processing ( 4 ), after the conversion of the digital signal into the frequency domain.
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