Examining the external, sidelong and internal music of Avestan Gāhān hymn

Gāhān is the oldest Iranian poem in the Avestan language. In this research, the external, sidelong and internal music of Gāhān are investigated. The data collection method is library-documentary and analytical research method. The study of ancient literary texts based on new literary criticism leads to a better understanding of them as the origin of Persian literature. The  external music surveys the metre. Gāhān has syllabic order. in sidelong music rhyme is explored, Gāhān has internal rythme. in internal music the repetition stylistics are so importante which are divided into visible and invisible. The  invisible repetitions used in Gāhān are redundant puns, subsequent pun, derivation and pseudo-derivation. Also single-place alliteration and multi-place alliteration are used in Gāhān. Gāhān’s Visible repetitions are repetition of words during a verse, regular repetition of one or more words at the beginning of verses, repetition of stanzas during a poetic form, repetition of one or more words sporadically in The length of a few verses, the regular repetition of one or more words at the beginning of the verses, and red Al-ajoz ala Al-sadr (Anadiplosis). endings  and declension, matching adjectives and pronouns with noun, prefixes and suffixes, repeating conjunctions, prepositions and adverbs also create music.Keywords: old Iranian poetries, Gāhān, poem’s music, external music, internal music, repetition.