We conducted a perception study on Mandarin, a tone language where pitch carries contrastive information, to investigate whether pitch changes interfere with spectral information in determining the number of syllables in an utterance. We generated F0 contours and simulated tonal coarticulation using the qTA model [1]. The perception of syllable numbers depended on the perception of tones, and this effect held across speech rate. Combining with prior work [2], the results indicate that laryngeal and supralaryngeal events interact in syllable perception in tone languages. We discuss how our findings support the notion of language-specific perception.