Comparison of F0 range in Spontaneous Speech in Kammu Tonal and Non-Tonal Dialects

The aim of this study is to investigate whether the occurrence of lexical tones in a language imposes restrictions on its pitch range. Kammu, a Mon-Khmer language spoken in Northern Laos comprises dialects with and without lexical tones and with no other major phonological differences. We use Kammu spontaneous speech to investigate differences in pitch range in the two dialects. The main finding is that tonal speakers exhibit a narrower pitch range. Thus, even at a high degree of engagement found in spontaneous speech, lexical tones impose restrictions on speakers’ pitch variation.