Give the TH Sound Its Own Space

Vietnamese speakers often replace the voiceless th in words like 'think' with a 'ch' sound, and the voiced th in words like 'this' with a 'z' sound, since neither exact sound exists in Vietnamese. The fix is a tongue-position change: instead of touching the roof of your mouth or the back of your teeth, let your tongue tip poke out gently between your top and bottom teeth and push air through for words like 'thanks,' or add a light voice buzz for words like 'that.' Try these slowly: think/ching, this/zis, three/chree — notice how different they feel once your tongue actually shows between your teeth. A simple two-minute exercise: look in a mirror and say 'this, that, think, three' five times, checking each time that your tongue tip is visible. It's a small physical habit, but once your mouth learns the new position, it becomes automatic — keep practicing a little every day!