| 摘要 |
PURPOSE: A varied characteristic compensated active noise cancelling with a feedback control is provided to prevent hard of hearing by attenuating external noise effectively. CONSTITUTION: In a varied characteristic compensated active noise cancelling with a feedback control, an earphone(100) is comprised of a first microphone(110), a second microphone, and a speaker unit. A first filter extracts a signal in a desired band from a signal of the first microphones. A first ADC(220) changes an extracted analog signal into a digital signal. A second filter(240) extracts a signal in an audible frequency band from an acoustic signal of a second microphones. A second ADC(250) changes the extracted analog signal into the digital signal. An adaptive signal processing unit(260) outputs a phase coefficient of a converted noise signal, a delay factor, an amplitude variance coefficient, and bandwidth frequency characterization factor at each band. The adaptive signal processing unit projects an optimum noise cancellation signal by detecting a residual signal. |
