The categorical perception of tones is based not only on word-internal F0 cues but also on external F0 cues in the contexts. The present study focuses on the effects of different types of preceding contexts on Mandarin tone perception. In the experiment, subjects were required to identify a target tone with the preceding context. The target tone was from a tone continuum ranging from Mandarin Tone 1 (high-level tone) to Tone 2 (mid-rising tone). It was preceded by four types of contexts (normal speech, reversal speech, fine-structure sound, and non-speech) with different mean F0 values. Results indicate that the categorical perception of Mandarin tones is influenced only by the normal speech context, and the effect is contrastive. For instance, in a normal speech context with a higher mean F0, the following tone is more likely to be perceived as a lower-frequency tone (Tone 2), whereas with a lower mean F0, the following tone is more likely to be perceived as a higher-frequency tone (Tone 1). These findings suggest that Mandarin tone normalization is mediated by speech-specific processes and that the speech context needs to be intelligible. [ABSTRACT FROM AUTHOR]