English /s/ vs /z/
bus vs buzz: silent throat or buzzing?

/s/ and /z/ are produced with identical tongue position and airflow -- the only difference is voicing. For /s/, the vocal cords are silent. For /z/, they vibrate. Put your hand on your throat: /sssss/ is quiet there; /zzzzz/ buzzes. That single on/off switch for vocal cord vibration separates "bus" from "buzz," "race" from "raise," and "price" from "prize."

The ABX drill plays two reference sounds then a mystery sound X. Choose which one X matches. The voicing contrast trains quickly with focused listening.

🔇Voicing only differs
👅Same tongue position
📝Very frequent in English
🔤Affects plurals & verb endings
Can you hear the difference?
How it works: You'll hear sound A, sound B, then a mystery sound X. Choose whether X matches A or B. Words are revealed after you answer.
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Listen carefully...

Mystery sound

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The problem

Why /s/ and /z/ collapse together in English spelling

English spelling actively hides the /s/-/z/ distinction. The letter "s" can be /s/ ("bus," "sun," "sky") or /z/ ("is," "was," "his," "dogs," "runs"). There is no consistent rule. The letter "z" is relatively rare and usually represents /z/, but provides no help predicting which pronunciation "s" takes. Learners must memorize voicing on a word-by-word basis, or learn the phonological rules (which are complex).

The second problem is that many languages lack this voicing contrast in certain positions. Spanish, for instance, has only /s/ as a distinct fricative in most positions (though [z] appears phonetically before voiced consonants). Japanese has /s/ and /z/ as separate phonemes, but their distribution differs from English. Korean similarly has /s/ but not /z/ distinctively.

The practical impact is enormous because the English plural, possessive, and third-person singular verb endings are all /z/ or /s/ depending on the preceding sound. "Dogs" ends in /z/, "cats" ends in /s/" -- a rule most learners never fully internalize.

What happens without training
  • ✗ "It's" sounds like "It's" but "Is" sounds like "Is-s" (too hissing)
  • ✗ "Price" and "prize" sound identical
  • ✗ "Bus" and "buzz" are indistinguishable
  • ✗ All English plurals sound over-hissed
What changes with ear training
  • ✓ You start catching the buzzing quality of /z/
  • ✓ /s/ and /z/ become reliably distinct
  • ✓ English word endings start sounding naturally correct
  • ✓ Minimal pairs like price/prize, race/raise clarify
Spanish speakers

Standard Spanish has /s/ but not /z/ as a distinct phoneme (except in contact with voiced consonants). Spanish speakers often devoice English /z/ to /s/, producing "buss" for "buzz," "raiss" for "raise," and "wass" for "was." This affects virtually every sentence with a plural or a verb ending.

Japanese / Korean speakers

Both Japanese and Korean have /s/ and /z/ in some form, but their distribution differs from English. Japanese /z/ often becomes [dz] initially and [z] medially; Korean has no voiced fricative /z/ phoneme. Speakers from these backgrounds may produce English /z/ inconsistently or devoice it in certain positions.

Arabic speakers

Modern Standard Arabic has both /s/ and /z/, which should help -- and Arabic speakers generally handle this contrast better than Spanish or East Asian speakers. However, dialectal differences (Levantine, Gulf, Egyptian) create variation, and the distributional rules for /s/ vs /z/ in English differ enough that errors still occur.

Production guide

How to produce /s/ and /z/

/s/s -- bus, race, sink, ice
  1. 1. Place the tongue tip near the alveolar ridge just behind the upper front teeth.
  2. 2. Create a narrow groove in the tongue and direct air through it.
  3. 3. Do NOT vibrate the vocal cords -- the throat should be silent.
  4. 4. The result is a sharp, hissing sound with no throat buzz.
Anchor words: sun, bus, race, ice, price, class, miss, pass, cats, books
/z/z -- buzz, raise, zinc, eyes
  1. 1. Same tongue position as /s/ -- tip near the alveolar ridge.
  2. 2. Same narrow groove and airflow direction as /s/.
  3. 3. ADD vocal cord vibration -- activate the throat buzz.
  4. 4. The result sounds like "sssss" but with a buzzing overtone underneath.
Anchor words: buzz, raise, prize, eyes, dogs, runs, was, is, his, jazz, zero
The hand-on-throat test

Place your hand gently on your throat. Say a long "sssss" -- your throat should be completely still. Now say a long "zzzzz" -- you should feel clear buzzing vibration through your hand. This is the voicing feature. Practice switching back and forth: "sssszzzzsssszzz" while keeping the tongue completely stationary. The only thing changing is the vocal cord switch.

The word-final voicing trap

In English, voicing at word endings is often reduced. "Buzz" may sound almost like "bus" to untrained ears because speakers sometimes devoice final /z/ slightly. The key perceptual cue is actually the vowel length: the vowel before /z/ is longer than before /s/. "Bus" has a shorter vowel than "buzz." In "race" /reɪs/ vs "raise" /reɪz/, the /eɪ/ diphthong is measurably longer in "raise."

Click to hear

Minimal pairs: tap each word to hear it

English word pairs where the only difference is /s/ vs /z/. Click each word to compare.

/s/ voiceless
/z/ voiced
a large road vehicle
↔
a humming sound
a competitive event
↔
to lift something up
the cost of something
↔
an award or reward
not tight or fixed
↔
to fail to win
a basin; to go down in water
↔
a metallic element
More /s/ words
busracepriceloosesinkicecatsbooksclassmisspasskissbasecase
More /z/ words
buzzraiseprizelosezincjazzdogsrunswasishisthesethosezero
Common questions

Frequently asked

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/s/ vs /z/ is just one English contrast

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