There are three ways to pronounce the words ending with -s:
- [s] after a voiceless sound such as k, f, p, t, or θ (voiceless sound produces no vibration of vocal chords): cats, hats, weeks
- [z] after a voiced sound such as ð, b, d, g, j, l, m, n, ŋ, r, v, w (voiced sound produces vibration of vocal chords): dogs, gloves, wolves, lives
- [ɪz] after these sounds: [tʃ], [dʒ], [s], [z] (because it would be impossible to pronounce such plural words without an additional sound [ɪ]: cockroaches, watches, bridges, buses, traces, blazes