Pronunciation and decoding exercises: /s/ vs /z/

The only difference betwen /s/ and /z/ is that /s/ is unvoiced and /z/ is voiced. See Voiced and unvoiced sounds.

The letter "s" is used to spell most words with /z/ and many words with /s/. Many students who are able to pronounce correctly both sounds may struggle with decoding writen words. For example, they may not be aware that goose doesn't rhyme with choose.

More detail can be seen in Advanced decoding exercises: /s/ vs /z/.

/s/

 * with initial /s/:
 * with "c": ceiling - cent - cinema - city
 * with "s":
 * with "sc": scene - scent - science


 * with final /s/:
 * with "ce": advice - choice - dance - nice - once - twice
 * with "s": bus - gas - this - yes
 * as morpheme “-s” for words ending in /f/, /k/, /p/, /t/, and /θ/:
 * as morpheme “-s” for words ending in /f/, /k/, /p/, /t/, and /θ/:


 * plurals: chiefs - ducks - cups - students - months
 * third person singular: laughs - thinks - helps - gets
 * possessives: staff's - Mike's - troop's - Egypt's - Edith's
 * with "se": dense - goose - house - loose - mouse - promise - release - tense
 * with "ss": boss - class - kiss - mass - miss


 * in mid-position:
 * with "c": cancel - concern - decide - receive - recent - society
 * with "s": analysis - awesome - basic - fantasy - nuisance
 * with "ss": assign - assume - lesson - missing - necessary - possible
 * with "ss": assign - assume - lesson - missing - necessary - possible


 * homophones: C - sea - see; cell - sell; cent - scent - sent; cite - site - sight; scene - seen;

/z/

 * with initial /z/: zapping - zebra - zoo;
 * with final /z/:
 * with "s": as - does - has - his - is - was
 * morpheme “-s”
 * plurals: bugs - churches - dens - keys - phones - shoes - toys
 * third person singular: comes - drives - gives - knows - tells
 * possessives: Alice's - Bob's - Carol's - Dave's - Ethiopia's - Finland's - Germany's
 * with "se": advise - browse - cheese - choose - lose - please - these - use - wise
 * with "zz": buzz - jazz
 * with "ze": breeze - freeze - sneeze


 * in mid-position:
 * with "s": busy - cousin - desert - easy - houses - music - poison - present - president - prison - reason - visit
 * with "ss": dessert - scissors
 * with "z": crazy - lazy - razor
 * with "zz": dizzy


 * homophones: browse - brows; nose - knows; size - sighs
 * homophones: browse - brows; nose - knows; size - sighs

At the beginning of the word

 * sue - zoo;

In mid position

 * lacy - lazy; precedent - president; racer - razor;

At the end of the word

 * advice - advise; bus - buzz; face - phase; hiss - his; grace - graze; loose - lose; price - prize; race - raise; rice - rise;


 * second word is plural: ace - A's; arse - R's; base - bays; case - K's; cease - seas/C's; decrease - decrees; dense - dens; dose - doughs; else - L's; force - fours; ice - eyes/I's; juice - Jews; lice - lies; niece - knees; once - ones; peace/piece - peas/P's; race - rays; since - sins; spice - spies; tense - tens; trace - trays; versus - verses;


 * second word is third person singular: dice - dies; false - falls; gross - grows; lice - lies; place - plays; sacrifice - sacrifies; scarce - scares;


 * Only in BrE: brass - bras


 * Only in AmE: loss - laws

Heteronyms

 * Noun is pronounced with /s/, verb is pronouced with /z/: abuse - excuse - house - use


 * close (adj.) - close (v.)

See also next section.

Devoicing
When two words are often pronounced together one of their consonants may influence the other. For example voiced /z/ and unvoiced /t/ become where /z/ is devoiced.


 * The verb suppose normally is /səˈpəʊz/ and its past tense normally is /səˈpəʊzd/. However suppose to and supposed to often are devoiced as /səˈpəʊs tə/ and /səˈpəʊst tə/.


 * Has to can be pronounced /hæs tə/.


 * Care should be taken to distinguish between "used to" and the past tense of the verb "to use": I used to /juːst tə/ use /juːz/ a laptop - He used /juːzd/ his laptop. - He didn't use /juːz/ his new shoes - He used to /juːst tə/ miss the last bus. - I used to /juːst tə/ go there to dance.


 * The word newspaper would normally be pronounced like news and paper /ˈnjuːzpeɪpər/ or /ˈnuːzpeɪpər/. Due to devoicing it can also be pronounced /ˈnjuːspeɪpər/ or /ˈnuːspeɪpər/.

Some curious contrasts
The first word is pronounced with /s/ and the second with /z/.
 * abusive - abuser; assess - possess; abyss - abysmal; crisis /ˈkraɪsɪs/ - crises /ˈkraɪsiːz/; divisive - divisor; exhibition /ˌksɪˈbɪʃən/ - exhibit /ɪɡˈzɪbɪt/; it's - he's, she's; louse - lousy;
 * These words don't rhyme
 * goose - choose; geese - cheese; promise /ˈprɒmɪs/ - compromise /ˈkɒmprəmaɪz/; Arkansas /ɑrːkənˌsɔː/ - Kansas /ˈkænzəs/; lease - please; purpose - pose;

Variant pronunciations
/s/ or /z/
 * opposite - transaction

/s/ or /z/
 * blouse - erase

Spanish
Most Spanish speakers cannot pronounce the /z/ sound. They won't even hear the difference between /s/ and /z/. See IPA phoneme /z/.

Other Romance languages
In most Romance languages "s" between vowels is pronounced [z]. For example Portuguese básico is pronounced [ˈbaziku], French basique is [bazik] and Italian basico is [ˈbaziko].