SPEECH RECOGNITION WITH LOW-COST MICROCONTROLLERS

Speech recognition tools for human-machine interaction (HMI) in consumer equipments have been recently become a reality because of the improvement in pattern recognition technologies, signal processing, and the development of high performance microcontroller devices at low-cost. In this paper, a compact system for phonemes and small vocabularies recognition is presented, its orientation being consumer applications, where cost is of paramount importance. The idea is that the user could operate a home appliance (TV set, washing machine, etc.) by means of speech commands. Thus, the speech recognition method must be as simple as possible, in such a way that could be implemented (programmed) onto a standard microcontroller device, with the requirements of a typical low-mid range embedded application: about 1 kilobyte of RAM memory, limited computing resources (8/16 bit integer arithmetic), low clock frequency (MHz), portability among different microcontroller architectures, low resolution A/D converters and low sampling frequency. First, the speech signal is sampled at 6K samples per second. Then, the Linear-Cepstrum (LFC) is used for speech processing because of its relatively low computational cost, in comparison with those techniques used in computer based applications (or with powerful DSP processors), as Mel-Cepstru