Voiced and unvoiced consonants. Many consonants in English are paired together because one is the unvoiced version of the other. They take the same mouth position, and the same tongue position. But in one of them, you just go 'hhh,' passing air. In the other one, you actually make a sound: uh, uh. For example: ch, ch. Only air is coming through my teeth. Jj, jj: I'm making an 'uh, uh' sound here.
Within the pairs, the unvoiced sounds are: tt, ff, pp, kk, th, ss, sh, ch. The voiced sounds of those are: dd, vv, bb, gg, th, zz, dj, jj. And in the consonants that have no pair, there is only
one that is unvoiced. And that is the hh as in 'hi.' The others are all voiced. mm, nn, ng, ll, rr, yy, ww.
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