The phonemic system of Karen is a somewhat complicated version of that reconstructed for Tibeto-Burman. Extensive phonetic reduction, often paralleling shifts found within Tibeto-Burman, has taken place, but the historical connection of the two systems can be established. Pwo has the following phonemes: k, χ, γ, t, d, s, ś, z, p, b, n, m, ʿ, θ, φ, r, l, y, w, h and?; i, e, ü, ö, ǝ, a, u and o. The consonant clusters, in initial position only, include kh, th, ph, sh (these might be regarded as unit phonemes); k or p ∼ b + y, w, r, or l (the w and l clusters are typical); my, ml and mw; tw, dw, nw, sw, χw, θw, yw, lw. The only vowel clusters are ai and au. The phonemic systems of Sgaw and (insofar as can be inferred from our meagre data) of other Karen languages are of the same general type as that of Pwo, with differences in detail rather than in outline.

Initial stops: Surd stops are maintained in Karen, usually in aspirated form (kh, th, ph):

Sgaw ka ‘open, diverge, dilate’; TB *ka.

Pwo kha-la?, Sgaw kha ‘chin’; TB *(m-)ka∼*(s-)ka.

Pwo and Sgaw kha ‘bitter’; TB *ka.

Pwo khu, Sgaw khü ‘smoke, vapor’; TB *kuw.

Pwo and Sgaw khe ‘tiger’; TB *d-key.

Pwo and Sgaw khwi<*khu-t ‘9’; TB *d-kuw.