You see the letter S, you say /s/. Logical, right? But when you say "music" the way it is written, you sound foreign. Native speakers say /ˈmjuːzɪk/. The S becomes a Z.
This is not an accident. There is a clear rule.
The Rule in One Line
When S sits between two vowels, it is almost always pronounced /z/.
Phoneticians call this intervocalic voicing. The reason is mechanical: vowels are voiced (your vocal cords vibrate). Stopping the voice for a quick /s/ and starting it again is harder than just keeping it on. So the S "borrows" the voice from the vowels around it and turns into /z/.
Quick Practice
Where the Rule Applies
Inside a Word
This is the most reliable case. Vowel + S + Vowel inside one word almost always gives /z/.
| Word | Sound | Says |
|---|---|---|
| visit | /ˈvɪzɪt/ | vi-zit |
| present | /ˈprezənt/ | pre-zent |
| resume | /rɪˈzuːm/ | ri-zoom |
| choose | /tʃuːz/ | chooz |
| noisy | /ˈnɔɪzi/ | noy-zee |
| husband | /ˈhʌzbənd/ | huz-band |
The Final E Trick
Many words end in vowel + S + silent E. The silent E still counts as a "vowel" for this rule, so the S says /z/.
- rose, nose, close (verb), pose, those, please, choose, lose
Plurals After a Vowel
When a noun ends in a vowel sound, the plural -s says /z/.
- boys /bɔɪz/, days /deɪz/, trees /triːz/, cars /kɑːrz/, cities /ˈsɪtiz/
The Exceptions: When S Stays /s/
The rule is strong, but not absolute. The main exceptions are short, common words and a small group of Greek/Latin roots.
Short Function Words
- this, that, thus, yes, us, plus, gas, bus – these keep /s/.
Words Built on the Root "base"
- basic /ˈbeɪsɪk/, basis /ˈbeɪsɪs/, basin /ˈbeɪsən/ – the root keeps /s/.
Verb / Noun Pairs
A few words use the S/Z difference to mark verb vs noun. Same spelling, different sound.
| Spelling | Noun /s/ | Verb /z/ |
|---|---|---|
| use | /juːs/ "the use of" | /juːz/ "to use it" |
| house | /haʊs/ "a house" | /haʊz/ "to house someone" |
| close | /kloʊs/ "close to me" (adj) | /kloʊz/ "close the door" |
| excuse | /ɪkˈskjuːs/ "an excuse" | /ɪkˈskjuːz/ "to excuse" |
The Easy Test
Want to know if your S is /z/? Hum the sound. If you can hum without breaking the airflow, it is /z/. If the sound is just hissing air, it is /s/.
Try it with "music": mmm-ZZZ-ic. You should feel a buzz on your throat.
Why This Matters for Listening
If you expect /s/ in "easy" or "music," your ear may miss the word entirely. Native speakers process the /z/ as the default. Train your ear to expect /z/ between vowels and English will suddenly sound less rushed.
Practice Sentences
Quick Summary
- S between two vowels = /z/ (rose, music, busy)
- S + silent E counts: vowel + S + e = /z/ (close, those)
- Plural -s after a vowel = /z/ (boys, trees)
- Exceptions: this, that, us, gas, bus, basic, basis
- Hum test: if you can hum, it is /z/
Once you internalize this, you will stop sounding stiff on dozens of everyday words.