 Tone terracing

Tone terracing is a type of phonetic downdrift, where the high or mid tones, but not the low tone, shift downward in pitch (downstep) after certain other tones.The result is that a tone may be realized at a certain pitch over a short stretch of speech shifts downward, then continues at its new level and then shifts downward again until the end of the prosodic contour is reached, at which point the pitch resets.