Downstep

Downstep is a phonological phenomenon in some tonal languages in which the pitch height of a following high tone is lowered relative to an earlier high tone. The result is a stepwise decline in the perceived pitch of consecutive high tones within an utterance. Downstep is typically triggered by the presence of a low tone or a floating low tone that lowers the register available for the next high tone.

Downstep is distinct from downdrift, which describes a broad, gradual lowering of the entire pitch range across an utterance, and from upstep, which is a temporary raising of pitch between tones. While downdrift reflects a persistent shift in the speaker’s pitch range, downstep is a local, discrete lowering that affects specific high tones in a sequence.

Analyses of downstep commonly invoke the idea of a floating low (L) tone or an L that relinks after certain segments. In autosegmental and other formal theories, the presence of a low target can depress the following high target, producing an H that is lower in absolute pitch than the preceding H. The effect is phonologized as an independent operation rather than as mere phonetic realization.

Surface realizations vary by language, but a typical pattern is H L H, where the second H is pronounced at a lower pitch than the first H. Downstep can interact with phonological phrasing and morphological boundaries, and it may occur within words or across word boundaries in some languages.

See also: downdrift, upstep, tonal languages, autosegmental phonology.