Non-native speakers of the English language tend to carry the intonation, accent or pronunciation from their mother tongue into the English speech. Some of the regional accents are easily identified with certain characteristics.
Another factor is how the English language is taught to young school children. If pronunciation is not taught correctly by the teachers, students will speak in the wrong way too. So there may be systematic mispronunciation coming from a country, such as India, Hong Kong, Malaysia, etc.
Origins in alphabetical order:
Australian: If you are American and you think they are a Cockney, they are an Australian.
Cantonese (Hong Kong Chinese):
- trouble with 'r', read as 'l' sound.
- trouble with 'v', read as 'w' sound.
- trouble with 'wh', read as 'w' sound.
- trouble with 'th', read as 'd' sound.
- trouble with most ending sound.
- trouble with past tense.
- forgetting to add 's' for plurals.
Cockney: If you are American and you think they are Australian, they are a Cockney.
East Asia (including Vietnamese, Chinese):
- due to the syllabic nature of their native languages, they tend to drop the ending sound of English words, e.g. 'ant' 'and' sound the same.
German:
- trouble with 'th', read as 'z'.
- 's' sometimes also read as 'z'.
- 'd' , 'g' or 'b' at end of a word read as 't', 'ck' or 'p'.
- German doesn't distinguish between verbs and adverbs, so Germans often drop '-ly' from adverbs.
Hebrew:
- Hebrew uses a palatalized ("soft") /l'/, whereas English uses a non-palatalized ("hard") /l/
- Hebrew has only 5 vowels and generally does not use diphthongs (except for foreign borrowings); they may therefore mispronounce some of the English vowels.
Japanese:
- trouble with 'l', read as 'r' sound.
- tend to over-stress ending sound, e.g. sound as soundo.
- often drop articles like "the" and "a"
- don't distinguish between singular and plural
Mandarin (Chinese):
- trouble with ending 'm' sound, there is no ending 'm' in Mandarin pronunciation, e.g. time read as tyne.
- confusion of 'he', 'she', and sometimes 'it', as all are one "word" in Mandarin Chinese.
New Zealander:
- sounds like Aussie, but can be distinguished by their pronunciation of 'six' as 'sex'
Persian:
- throat noise in 'k' sound.
Russian:
- often a palatalized dental /r'/ is used before vowels, which is absent in English.
- lack of differentiation between /x/ (as in "Jose") and /h/ (as in "hot")
The Subcontinent:
- Questions worded like statements. Detected by native speakers because of stress on verb in case of questions
- Using 'ing': Instead of "He has a car", "He is having a car"
Swedish:
- sing-songy intonation. Swedes often speak English with a melodic intonation, ending sentences on an up-note, much parodized (the Swedish chef from The Muppet Show is a well known example and a Usenet institution.)
- trouble with the ending -ed, as the following sentence (from the parody sitcom Soap): "Do you think I'm finished?" (pronounced "Finnish"). Answer: "No, Swedish!"
USA (Midwest and West Coast):
- /O/ merged with /a/. "not" sounds like "naht" (/nOt/ --> [nat]), "opportunity" like "ahppertunity"
- preservation of non-prevocalic r
- (near Canadian border:) monopthongization of /ow/ as [o], eg. most dialects "boat" /bowt/ --> "boot" [bot].
USA (South):
- monopthongization of /ay/ as [a:], eg. most dialects' "I" --> "Ah" in the South.
- (also some East Coast:) loss of non-prevocalic r.
- slower speech tempo
USA (New England and East Coast):
- (also South:) loss of non-prevocalic r in some dialects.
- faster speech tempo