oi/oy sound

Rule Core

oi / oy represent the English diphthong /ɔɪ/, a smooth glide from a rounded back vowel to a short front vowel. In spelling, oi typically appears at the beginning or middle of words (coin, noise), while oy usually occurs at the end (boy, toy). This pattern is highly consistent in phonics.

Articulation Guide

Start with rounded lips and a slightly retracted tongue position. Then quickly relax the lips, moving the tongue forward and slightly upward. Maintain continuous airflow to preserve the diphthong glide.

Word Analysis (with buy)

boy /bɔɪ/: a classic oy example with a clear /ɔɪ/ glide. coin /kɔɪn/: oi in medial position, same sound. buy /baɪ/: often confused with oi/oy, but this word uses /aɪ/, starting from an open vowel, not the rounded /ɔ/.

Pitfalls to Avoid

Do not pronounce oi/oy as a pure /o/ or /i/. Also, avoid assuming that all words ending in y share the /ɔɪ/ sound.