Original sentence: Some languages spoken by immigrants are also frequently heard, especially in large cities: Portuguese, Maghreb Arabic, several Berber languages, several languages of Sub-Saharan Africa, Turkish, several spoken variants of Chinese (most notably Wu dialects, Cantonese, Min Nan, and  Mandarin), Vietnamese, and Khmer are the most frequently heard
Edited sentence: Some languages spoken by immigrants are also frequently heard, especially in large cities: Portuguese, Maghreb Arabic, several Berber languages, several languages of Sub-Saharan Africa, Turkish, several Chinese dialects (most notably Wu dialects, Cantonese, Min Nan, and  Mandarin), Vietnamese, and Khmer are the most frequently heard