The spelling of the word "SEX AV CH" follows a phonetic transcription of its pronunciation. In IPA, the word is spelled /sɛks æv tʃ/. The first syllable is spelled with an "e" instead of an "i" because it follows the short "e" sound (/ɛ/) rather than the long "i" sound (/i:/). The second syllable is spelled with "av" instead of "of" because it follows the /æ/ sound. The final sound is spelled with "ch" rather than "tsh" because it is a voiceless affricate (/tʃ/) rather than a voiceless alveolar stop (/tʃ/).