母语经验影响成人习得其他语言的语音。本文选取普通话母语人听感粤语声调来探讨这一议题，借用知觉同化模型检测了粤语双字词中的声调与普通话声调在听感上的相似度，同时验证了语音环境对声调感知的影响。我们发现粤语中平调较多被同化为普通话第一声，粤语低平调被同化为普通话第三声，粤语低降调则没有对应被同化的普通话声调。声调在双字词内的位置也影响了感知结果。除了高平和低降调外，粤语其它声调在词首更多被同化为普通话第三声，这与普通话第三声在语流中的变化有关。另外，粤语低平调在词尾时更不易被同化为普通话的声调类别，这与普通话较少在词尾出现低降调有关。总之，声调感知受母语语音和音系经验影响，这对声调语言的语音教学有一定的启发意义。

Adults’ second language (L2) acquisition, including that of speech sounds, is affected by their first languages (L1s). Aiming at the impact of L1-L2 shared features in sound inventories on L2 speech acquisition, our study adopted the Perceptual Assimilation Model to examine the assimilation of Cantonese tones into Mandarin tonal categories by Mandarin learners of Cantonese. We also assessed effects of phonetic contexts on tone perception by varying positions of tones within bi-syllabic words. Results showed that Cantonese mid-level tone (CT3) and low-falling tone (CT4) were perceptually similar as Mandarin high-level tone (MT1) and falling-and-rising tone (MT3) respectively. Cantonese low-level tone (CT6) could not be assimilated as Mandarin tones. CT4 at word-final positions was less frequently assimilated than word-initially. Except for the high-level tone (CT1) and CT6, all other four tones in Cantonese at word-initial positions were assimilated as MT3 more frequently than they were at word-final. The perceptual asymmetry can be attributed to listeners’ experiences in tone sandhi of MT3 in connected speech and in allotones of others in various tonal contexts. Our study confirms that the perception of L2 tones by tonal speakers is affected by both phonetic and phonological factors in L1 and L2. Our findings also provide implications for teaching and learning Cantonese tones.