This study investigated the possibility of pitch and tone register differences between native speakers of Taiwan and Beijing Mandarin by means of an acoustic analysis of three speech styles. Speech styles included spontaneous interview, spontaneous descriptive, and controlled read sentential speech. Data analysis included long segments of recorded speech in order to discern any statistically significant pitch register differences between the two dialects. Speech style and read tones were also analyzed. Results suggest that tones produced in Taiwan Mandarin are in a slightly lower register than those produced in Beijing Mandarin. Surprisingly, speech style was not a significant predictor of pitch register in long segments of recorded speech. Despite a limited sample size, this research effectively promotes the inclusion of sociolinguistic variables such as dialect in the field of tone research.