Subband normalization, transformation, and voiceness to recognize

Abstract

A radio communication system includes a voice recognition system (221) for converting (400) a caller's voice message to a textual speech message. The textual speech message is then transmitted to an intended selective call radio (122). To perform these functions, the radio communication system includes a caller interface circuit (218), a transmitter (116), and a processor (222). To perform voice-to-text conversion, the processor is adapted to cause the caller interface circuit to sample a voice signal generated by the caller during a plurality of frame intervals, and to apply a Fourier transform thereto, thereby generating spectral data. The spectral data is subdivided into a plurality of bands. The spectral envelope of the spectral data is then filtered out to generate filtered spectral data. A Fourier transform is applied thereto to generate an autocorrelation function for each band. From the autocorrelation function of each band, a magnitude is determined, which is representative of the degree of voiceness of each band. The degree of voiceness for each band is then applied to a corresponding plurality of phoneme models, which are used to derive a textual equivalent of speech from the voice signal. The textual equivalent of speech is then transmitted to the selective call radio by way of the transmitter.