English as a second language; ESL; TESOL ; Listening comprehension ; Sprachattitüde; Linguizismus; Linguicism; Prestige; Sprachliche Unsicherheit; Linguistic insecurity ; Kulturvergleich; Language and culture ; Phonische Interferenz; Languages in contact (phon.) ; Sprachkontakt (phon.) ; Interference (phon.) ; English ; Vietnamese