Is s voiced or voiceless?
Voiceless consonants do not use the vocal cords to produce their hard, percussive sounds. Instead, they're slack, allowing air to flow freely from the lungs to the mouth, where the tongue, teeth, and lips engage to modulate the sound. These are the voiceless consonants: Ch, F, K, P, S, Sh, T, and Th (as in "thing").
What is the rule for S making the Z sound?
Say “Z when the word ends in a vowel or other voiced sound like the m, n, ng, l, b, d, g, v, voiced th, or r sound. Say “S when the word ends in a voiceless sound like a p, t, k, f, or voiceless th sound.