Segment-based apparatus and method for speech recognition by analyzing multiple speech unit frames and modeling both temporal and spatial correlation

In a digital processor, a method for decoding an input speech signal to a corresponding speech unit comprising the steps of:

• providing an input speech signal formed of multiple observation frames;
• providing a plurality of unit templates in stored memory of the digital processor, each unit template for representing acoustic attributes of a respective speech unit and for generating a respective target speech unit;
• providing a plurality of error models associated with the unit templates in stored memory, each unit template having an error model for explicitly measuring and quantitatively representing temporal and spatial correlations between the synthetic segments and a subject speech signal, the temporal and spatial correlations being between acoustic attributes in the observation frames of the subject speech signal;
• receiving the input speech signal in working memory of the digital processor;
• comparing the target speech units with different plural observation frames of the input speech signal in working memory such that the comparison defines a set of error sequences in working memory;
• and
• using the error models, analyzing the error sequences and determining the corresponding speech unit of the input speech signal.

In a digital processor, speech recognition apparatus for decoding an input speech signal to a corresponding speech unit, the apparatus comprising:

• a source providing an input speech signal formed of multiple observation frames;
• a plurality of unit templates, each unit template for representing acoustic attributes of a respective speech unit and each unit template generating a respective synthetic segment indicative of the respective speech unit;
• a plurality of error models associated with the unit templates, each unit template having an error model;
• and
• processor means coupled to the unit templates and error models and coupled to the source to receive the input speech signal, the processor means comparing the synthetic segments to different plural observation frames of the input speech signal to define a set of error sequences, the processor means transforming each error sequence to a fixed dimension error feature vector independent of the number of observation frames, and based on the error models, the processor means computing a score for the error feature vector.