| 摘要 |
PROBLEM TO BE SOLVED: To provide a howling canceller capable or preferentially opening a notch filter inserted at a frequency where howling can be easily removed depending on a change in an acoustic feedback system. SOLUTION: A filter coefficient generating section 12 of the howling canceller 1A stores an opening time of each notch filter 13 and opens the notch filter 13 which has reached the opening time. Generally, a frequency at which howling occurs depends on an installation environment or a utilization status or the lie. Meanwhile, howling occurs when a loop gain increases resulting from the aligning of a phase and exceeds by 1 in a closed loop from a speaker to a microphone. That is, low frequencies have small influences of phase shifts caused by the movement of a microphone because they have long wavelengths, and are imposed by the influence of reflection on a wall or the other installation environment. On the contrary, high frequencies have large influences of phase shifts caused by the movement of the microphone because they have short wavelengths. In order to solve the problem, the filter coefficient generating section 12 sets the opening time of each notch filter to be shorter as the frequency at which the notch filter is inserted increases. COPYRIGHT: (C)2011,JPO&INPIT |
