A predefined command recognition system using a ceiling microphone array in noisy housing environments

This paper describes a speech recognition system that detects basic voice commands for a mobile robot operating in a home space. The system recognizes arbitrary timed speech with position information in a noisy housing environment. The microphone array is attached to the ceiling, and localizes sound source direction in azimuth and elevation, then separates multiple sound sources using delay and sum beam forming (DSBF) and frequency band separation (FBS) algorithm. We implement the sound localization and separation method on our 32 channel microphone array. The separated sound source is recognized using an open source speech recognizer. These sound localization, separation and recognition functions are implemented as online processing in real world. We define four indices to evaluate the performance of the recognition system, and the efficiency in a noisy environment or with distant sound sources is confirmed from experiments in varied conditions. Finally, an application for a mobile robot interface is reported.