/ɔɪ/

The /ɔɪ/ diphthong is a smooth glide between two vowel positions. Your mouth and tongue move continuously as you produce this sound.

Starting position: Begin with your jaw moderately open and your lips rounded into an "o" shape. Your tongue should be positioned at the back of your mouth at a mid-low height - similar to the vowel in "thought" or "law."

The glide: As you voice the sound, let your jaw close slightly while your lips gradually unround and relax back. At the same time, your tongue moves forward and arches upward toward the front of your mouth.

Ending position: Finish with your tongue high and forward, lips relaxed and unrounded - close to the short /ɪ/ sound in "bit" or "sit."

The transition should feel like one connected motion, not two separate sounds. Let your mouth flow naturally from the rounded back position to the unrounded front position.

This sound has two main spelling patterns:

• oi: coin, join, voice, choice, point, noise, moist
• oy: boy, toy, joy, enjoy, destroy, royal, loyal

A helpful pattern: "oi" typically appears in the middle of words, while "oy" usually comes at the end.

Focus on starting with rounded lips - that "o" shape is essential. If you skip the lip rounding at the beginning, the sound may come out flat or be confused with /aɪ/ as in "buy." Try exaggerating the round-to-relaxed lip movement at first, then let it become more natural with practice.