The letters of the Hebrew alphabet are usually classed in the following manner:
Gutturals = A, H, Ch, O (R by some).
Palatals = G, I, K, Q.
Linguals = D, Th, T, L, N.
Dentals = Z, S, Sh, Tz (R by others).
Labials = B, V, M, P.
The “Sepher Yetzirah” further classes them as—
3 Mothers (Primitives) = A, M, Sh.
7 Duplicated = B, G, D, K, P, R, Th.
12 Simples = H, V, Z, Ch, T, I, L, N, S, O, Tz, Q.