Speech interval establishment unit for speech recognition system - operates in two stages on filtered, multiplexed and digitised signals from speech and background noise microphones

摘要

The signals from two microphones (1,2) at unequal distances from the speaker are processed by separte amplifiers (11,21), band-pass filters (12,22), rectifying circuits (13,23), low-pass filters (14,24), multiplexers (15,25) and A/D convertors (16,26). An internval recognition unit (30) operates on the difference between the aggregate powers of the acoustic signal (X(i)) and the spectrum (N(i)) of a periodic ref. signal in a preset time frame. A noise coefft. calculator (40) and canceller (50) produce a speech spectrum (S(i)) for threshold comparison in a second stage of recognition (60). USE/ADVANTAGE - In noisy environment, e.g. in , factory, home. Speech or voice intervals can be recognised adequately. even in extreme conditions of irregular noise.