1. INTRODUCTION
Speech is varied and diverse; and it largely depends on the geographical and social dialectal features of the speaker. Speech recognition systems are mostly trained using mainstream or standard language data, and therefore they frequently show decreased accuracy when recognizing utterances that diverge from the standard form [1]. A growing body of research has begun to investigate this problem, such as vowel variation in French-Algerian Arabic [2], lenition of voiced stops and coda /s/ in Spanish [3], and regional variation of /r/ in Swiss German [4].