Patent ID: 7912230
Filing Date: 2011-03-22
Classification: H04R

Abstract:
1. A howling detection device for detecting a dominance ratio, which indicates a risk of howling to occur when a mixed signal obtained by a sound mixing section for mixing a plurality of sound signals respectively collected by a plurality of microphones is outputted by a speaker, the howling detection device comprising: a level detecting section configured to respectively detect levels of the plurality of sound signals; a word ending detecting section configured to compare, in a same time domain, the mixed signal with a signal regarding a sound to be outputted by the speaker as a noise reference signal and detect a time period, as a word ending section, during which the mixed signal is inputted after the noise reference signal falls; a dominance ratio calculating section configured to extract only a level of the word ending section from each of the levels of the plurality of sound signals detected by the level detecting section and calculate, as a dominance ratio, a ratio of the extracted level of each of the sound signals to a sum of extracted levels of the plurality of sound signals; and a howling suppressing section configured to subtract, from the mixed signal, a signal having a same component as a signal included in the word ending section, based on a transfer characteristic calculated by using the dominance ratio, and output the obtained signal to the speaker.