from: http://ucalgary.ca/dflynn/consonants

Here are the English sibilants:

s in 'bus'
z in 'buzz'
in 'hush'
in 'leisure'
in 'church'
in 'judge'

Sibilants are the "s"-like sounds, the whistling fricatives . In Icelandic there's only one - s, which is alveolar andunvoiced. This means that Icelanders are not used to pronouncing postalveolar sibilants, and no voiced sibilants at all.

This is problematic, because the differences between the English sibilants is very distinctive in English, and Icelanders tend to pronounce them all the same.

Problem 1: lack of voicing

In the Language Lab, listen to see whether you make these distinctions:

Sue - zoo -

price - prize -

base - bays -

busing - buzzing -

It's common in 'Icelandic English' to pronounce these pairs of words the same - as homophones. In order not to do this, you should remember

that z is VOICED, especially at the beginning of words (zoo) and between syllables (buzzing)
that if the vowel is tense (or a diphthong) it will be LONGER before z than before s - in prize and bays.

Problem 2: articulation

In the Language Lab, listen to hear whether you make these distinctions:

save shave -

gas gash -

presser pressure -

Here it's important to make an articulatory distinction between s and sh. Try not to use the Icelandic method of putting j(as in yellow) after the s, and saying sjopp for shop. THIS IS ESPECIALLY IMPORTANT when "i" occurs in the spelling:

mission, nation -- ,
NOT:
miss-i-on, nat-i-on

Problem 2: Voicing.

In the Language Lab listen to hear if you make these distinctions:

racer razor -

mission vision -

batch badge -

How can we tell whether s (in spelling) is s or z in pronunciation?

There are 2 answers to this question, depending on whether the written s is an inflectional ending or not. By inflection, we mean -s or -es or -'s in words like:

loves( 3rd. person singular present of the verb:'She loves Selfoss' )

cats (plural)

John's (possessive)

the girls' (plural possessive)

's = is (Mary's leaving)

's = has (Mary's gone)

S: Spelling and Pronunciation

In order to work out whether the sound is S or Z, you have first to ask:

Is it an inflection or not?

Remember, by "inflection" we mean any of the following:

loves( 3rd. person singular present of the verb:'She loves Selfoss' )

cats (plural)

John's (possessive)

the girls' (plural possessive)

's = is (Mary's leaving)

's = has (Mary's gone)

INFLECTIONAL -S

First, FIND THE SOUND IMMEDIATELY PRECEDING THE INFLECTION.
For example:

loves /

/ - the preceding sound is the lenis fricative

wants /

/ - the preceding sound is the fortis plosive

sees /

/ - the preceding sound is the vowel

voices /

/ - here the ending is -

. (This means that some speakers have -

, and others have -

). - The sound immediately preceding the ending is

As we can see, there are 3 possible endings:

after SIBILANTS or s-sounds (voices, watches, dishes, barges, the Jones's, Magnus's, buses)

after FORTIS CONSONANTS (other than sibilants) - i.e. after

(tops, Dick's, rats, laughs, paths)

after EVERYTHING ELSE (all other consonants and all vowels) - (robs, hugs, spades, trees, leaves, bathes, Joe's, Ann's, things, ends, he's, she's, cars, spiders...)

We can show this diagramatically:

LEXICAL S

When s is not inflectional, when it is part of the word, and so "lexical", it's not always so easy to work out the pronunciation. - We'll also consider the other sibilant SPELLING FORMS under this section - z, c, ss, ti and so on.
There are a few rules which will help us, but much of the time you'll need to consult a dictionary. Most of these rules seem to work fairly well:

's' at the beginning of words is pronounced /s/ (unvoiced) - see, stop, Sue.
's' at the end of words, when it is not inflectional, is usually /s/ (unvoiced) - crisis, curious, Magnus, us (but 'as' has /z/). In 'has' and 'does' the -s is inflectional, and voiced - , .
'z' is always voiced /z/ - zoo, zink, prize, crazy, buzz, quiz. But 'tz' is /ts/ - waltz //, Ritz //
'c' before 'e', 'i', 'y' is always /s/: price, voice, cellar, cylinder, recite.
'ss' is usually /s/ (unvoiced) - kiss, kissing, fusser, lesson, massive -- but not always! For instance, 'dessert' (= sweet course at the end of a meal) is pronounces like the verb 'to desert', both with z and the accent on the second syllable - // (but the noun 'desert' has the accent on the first syllable: //.) - Other exceptions are 'possess' //, 'scissors' //, 'dissolve' // (like resolve' //) - but compare 'dissolution'//.
'ss' is pronounced // (unvoiced) inwords like pressure', //.
'ssi' and 'ti' are pronounced // (unvoiced) in words like 'mission' //, 'nation // - note the 'i' is silent.
'si' and 'su' are pronounced // (voiced) in words like 'vision' //, 'pleasure' //.