Chinese · Pronunciation Guide
mahn, dropping hard from high to low. Ordinary m, a broad open vowel, and a front n.
màn
Its own drop is fixed, and it sets off the 不 change: bú màn. Compared with 快 kuài, both members of the fast-slow pair are fourth tones, so tone offers no help distinguishing them — the work is done entirely by the consonants and the finals.
Listen: 慢
Free browser voice. Hear it read by a real native speaker inside the LingoDrop app.
今天火车很慢。
Jīntiān huǒchē hěn màn.
The train is slow today.
Listen: 今天火车很慢。
Free browser voice. Hear it read by a real native speaker inside the LingoDrop app.
今天火车很慢。 puts huǒchē in the middle, where huǒ is a dipping tone followed by the level chē, so no sandhi fires there. Hěn then keeps its full dip before the falling màn. That gives two separate unchanged third tones in one sentence, which learners often assume must have combined somehow.
The standard casualty is the vowel, produced as the flat front a of English "man" rather than the open "ah" of "father". Drop the jaw. The nasal is the second issue: máng with a back nasal is a real and common word meaning busy, so the merger genuinely changes the sentence — and since both words appear in the same slot, context will not always save you.