Which symbol is used to indicate the diphthong sound in 'boy'?

The symbol that indicates the diphthong sound in 'boy' is /ɔɪ/. This phonetic representation captures the unique glide from the open-mid back rounded vowel sound, represented by /ɔ/, to the near-close near-front rounded vowel sound, represented by /ɪ/.

In the case of 'boy', the pronunciation begins with the /ɔ/ sound as in "law," transitioning into the /ɪ/ sound, similar to the vowel sound found in "bit." This glide from one vowel to another within a single syllable creates what is characterized as a diphthong. Therefore, /ɔɪ/ accurately reflects how the word 'boy' is articulated in phonetic terms.

The other symbols do not represent the correct sound for 'boy.' For instance, /aɪ/ corresponds to the diphthong in 'my,' while /eɪ/ represents the sound in 'day,' and /oʊ/ corresponds to the diphthong in 'go.' Each of these examples illustrates different vowel combinations, emphasizing the importance of the /ɔɪ/ symbol specifically for 'boy.'