Utterances like /xob/(okay), /doroste/(right), /hmm/, /ee/, /are/(yeah) occur frequently in Persian conversations, but have thus far scaped from the systematic studies. Godd 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 channelling vary from one context to another. The usage of back channel responses is different in various contexts, due to poilitness or informality. This paper studies the types and functions of the back of these responses in both formal and informal settings and provides a comparison of 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.

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