s as z

Core Rule

The /z/ sound of s appears when s is between vowels, follows a voiced sound, or functions as a plural/possessive ending after a voiced phoneme. This reflects English voicing assimilation.

Articulation Guide

Place the tongue lightly on the alveolar ridge, keep the mouth relaxed, and vibrate the vocal cords. Air flows continuously with friction.

Word Analysis

• phase /feɪz/: s between vowels → /z/
• possess /pəˈzɛs/: intervocalic s → /z/
• possessive /pəˈzɛsɪv/: derived form keeps /z/

Pitfalls

Don’t pronounce every s as /s/. Check voicing, not spelling alone.