Mandarin Neutral Tone—does it Change Target

It is known that in Mandarin each of the five lexical tones can be assigned with an articulatorily functional target: [high] for tone 1, [rise] for tone 2, [low] for tone 3, [fall] for tone 4 and [mid] for tone 5 (the first four tones are known as full tones while tone 5 is called neutral tone). Given that the targets of full tones can change (e.g., from tone 3 to tone 2) in certain speech conditions (e.g. tone sandhi), it is natural to ask whether the same is true for Mandarin neutral tone. This is still an unresolved question, the solution of which can contribute to our understanding of articulatory “strength” as an index of speech communication which is less well explored than other areas of speech production. Motivated by the above concerns, this study uses speech production experiment to test whether the target of Mandarin neutral tone has similar target values (in terms of target slope, height, duration and strength) to those of other tones in Mandarin under three speech conditions: emotion (anger, happiness, disgust and neural emotion), sentence position of the neutral tone (sentence medial and final) and tones preceding the neutral tone (all full tones in Mandarin). The results reveal that the neutral tone is highly likely to change its target in certain combinations of the aforementioned three speech conditions. This study not only further supports previous studies on the impact of emotion, sentence position and tonal contexts on the target behavior of tones, but also highlights the possibility of Mandarin neutral tone changing from weak to strong in articulation for the purpose of effective communication, providing further evidence for “strength” as a communication index.