摘要：Utterances like /xob/ (okay), /doroste/ (right), /hmm/, /ee/, /are/ (yeah),occur frequently in Persian conversations, but have thus far escaped from the systematic studies. Good listeners generally produce these short utterances, called "back channel responses", in appropriate times to show their participation in the conversation, but the rules governing back channeling vary from one context to another. The usage of back channel responses is different in various contexts, due to politeness or formality. This paper studies the types and functions of the back channel responses in both formal and informal settings and provides a comparison of the usage of these responses in these two kinds of contexts. The results show /bale/(yes) and /doroste/(right) are used with formal or polite verbal form, while /xob/ (okay) is used with the informal style of speech and less polite verbal form. With respect to the function of back channels, signaling the understanding is the main function of back channels in informal contexts. Also, back channels signaling agreement are more frequent in formal contexts, where emotional function is less likely
