A phonetic variation model building apparatus, having a phoneme database for recording at least a standard phonetic model of a language and a plurality of non-standardized phonemes of the language is provided. A phonetic variation identifier identifies a plurality of phonetic variations between the non-standardized phonemes and the standard phonetic model. A phonetic transformation calculator calculates a plurality of coefficients of a phonetic transformation function based on the phonetic variations and the phonetic transformation function. A phonetic variation model generator generates at least a phonetic variation model based on the standard phonetic model, the phonetic transformation function and the coefficients thereof.