Patent ID: 8532986

Claim:
A speech signal evaluation apparatus comprising: a processor; and a memory storing speech signals and a plurality of instructions, which when executed by the processor, cause the processor to execute, acquiring, as a first frame, a speech signal of a specified length from the speech signals stored in the memory; detecting, on the basis of a speech condition indicating a presence of speech, whether the first frame is voiced or unvoiced, wherein an unvoiced frame does not satisfy the speech condition and a voiced frame does satisfy the speech condition; calculating, when the first frame is unvoiced, a variation in a spectrum associated with the first frame on the basis of a spectrum of the first frame and a spectrum of a second frame, the second frame being unvoiced and preceding the first frame in time; and detecting, on a basis of a non-stationary condition based on the variation in spectrum, whether the variation satisfies the non-stationary condition, wherein the variation in the spectrum is calculated on the basis of an absolute value of a difference between the spectrum of the first frame and the spectrum of the second frame at each frequency.