Taiwan mandarin - Does it remain homogeneous?

Previous studies have shown discrepancies in tonal realizations between Guoyu and Putonghua. Early studies suggests Guoyu T3 is predominantly a falling tone and recent studies show Guoyu T2 is predominantly a dipping tone, contrastive to the long-considered default dipping and rising tone respectively. This study further explores the existence of regional varieties of Guoyu. Data are collected from Taipei and Taichung. Speakers read target sentences with 19 minimal pairs of final T2/T3 syllable being placed sentence final. Results indicate regional differences of T2/T3 patterns. The result of Taipei speakers indicates a clear distinction of T2/T3 contour in that T2 is realized as a mid-dipping contour and T3 either a mid-dipping or a mid-falling contour, with the latter as the majority. However, in the Taichung dialect, this distinction disappeared. It is shown that Taichung T2 contour has changed from mid-dipping to mid-falling, merging with T3. This merger is statistically significant.