Studies have shown that native speakers of Mandarin Chinese and Hong Kong Cantonese tend to have difficulty perceiving the English fricative /θ/. However, although both languages have /f/ and /s/ categories, Mandarin speakers tend to assimilate it to their /s/ category whilst Cantonese speakers would assimilate it to their /f/ category. Over three studies, this thesis investigated various factors that may lead to this difference, while enhancing our understanding of the acoustics and the perception of the fricatives of these languages. Study 1 explored acoustic properties of target fricatives of the three languages (Mandarin, Cantonese, English) using audio recordings from native speakers, and conducted comparisons of the fricatives within and across languages. The results showed that the phonemes /f s/, even though shared by the three languages, were produced differently in the different languages, likely due to the effects of the different fricative inventories. Moreover, different acoustic cues were more or less effective in distinguishing between the different fricatives in each language, indicating that native speakers of these languages likely rely on these cues differently. Study 2 examined how transition cues may affect the identification of /f/ and /s/ by native speakers of the respective languages by combining a phoneme monitoring task and EEG measures. Target fricatives were spliced with vowels to create stimuli with congruent or incongruent transitions. In contrast to previous studies (e.g., Wagner, Ernestus & Cutler, 2006), the results revealed that all groups attended to formant transitions when processing fricatives, despite their differing native fricative inventory sizes. Study 3 investigated cross-language differences in categorisation boundaries of target fricative pairs using a behavioural identification task. The study interpolated pairs of stimuli to create a frication continuum and a vowel continuum, forming a 2-dimensional stimuli grid. The results indicated that frication was the primary cue for fricative identification for the native English, Cantonese, and Mandarin speakers, but also revealed cross-language differences in fricative boundaries. Overall, the results of these studies demonstrate that the processing of fricatives was largely driven by the frication section, and the differential assimilation of /θ/ was likely due to the different acoustics of the same fricative category across languages. The results also motivate a reconsideration of the role of coarticulatory cues in fricative perception
