Pre-howling howlback detection method

This report relates to a howling detection unit used in teleconferencing systems, one which is capable of detecting howling before it occurs. An analytical study was made of the characteristics of pre-howling conditions, in which it was found that howling components are present immediately following spoken syllables in conversational speech. Based on these results, the differential value of signal amplitude was employed to extract these howling components, thus creating a new howling detection method for frequency analysis. Computer simulation confirmed that howling components can be detected accurately using this detection method, even under pre-howling conditions of howlback margin 3dB. This system was implemented on a trial basis, using a Digital Signal Processor, and favorable results were obtained.