Tone-3 accent realization in short Chinese sentences

To investigate how a low tone (tone-3, T3) syllable in Chinese can be perceived to be focal accented or not, a total of 156 sentences containing tone-3 words were synthesized and used as stimuli in a perceptual study. The sentences differed in the falling value between the two high pitches, and in the duration and phonation types of the T3 syllables. Thirty-nine subjects were asked to judge where the focus or accent was for each sentence. The results show that at least three degrees of pitch drop are involved in the focus recognition: a big sized drop of about 10 semitones; a middle sized drop of about 6 semitones; a small sized drop of about 2 semitones. The results suggest that the three sizes of pitch drop have different indications in Chinese intonation, depending on both the tone and the tone combination. In perception, there are various ways to realize tone-3 focus in the Tx-T3-Ty sentences series, but in production or for text-to-speech synthesis, the rule simply is making a middle sized pitch drop with a long and creaky T3 syllable. Similarly, to focus on the low tone syllable in the T3-Tx-Ty sentences, a creaky T3 syllable is essential. However, a long T3 syllable is a strong determinant for a low tone focus in the Tx-Ty-T3 sentences.