The word "啊哟" is formed by combining two phonetic characters, "啊" (ā) and "哟" (yō), which are interjections used solely for their sounds to create a compound exclamation. Each character contributes its syllable to produce a reduplicative expression that mimics a sudden vocal reaction, often conveying emotions like surprise or pain. This construction relies on auditory imitation, resulting in a word that functions as an emotional utterance without semantic meaning derived from the individual characters.