Abstract
This study investigates directional constraints on diachronic tone chain shifts and their applicability to non-chain shifts. Twenty-eight chain shift changes from 12 Sino-Tibetan, Kra-Dai, Austronesian, and Otomanguean languages were compared to a sample of 118 non-chain shifts (including merger) from 54 Asian tone languages. Significant overlap was found: the reported chain shift changes were also the most frequently occurring changes in non-chain shifts. Recurring patterns emerged in both chain shifts and non-chain shifts: (1) tonal alignment slides rightward, with effects on contour shape, f0 excursion and f0 onset height; and (2) falling tones become higher while rising tones lower. These crosslinguistic diachronic trends show parallels to tone variation in connected speech, which suggests that the direction of diachronic tone change is phonetically grounded, constrained by articulatory and cognitive biases in speech production and perception.