Pronouncing verb and noun inflexions

endings

English is, in general terms, a non-inflecting language.
However, of the limited inflexions the language does have, verb and noun endings can cause pronunciation problems and can be the source of a foreign accent, even at quite advanced levels.
Some time spent, therefore, on explaining and practising the way we pronounce verb and noun inflexions can pay dividends.

Fortunately, there are few to deal with and some (the -s and -es endings, in particular) serve multiple purposes and obey the same pronunciation rules.
It is often said that English is wholly irregular in terms of there being no obvious relationship between spelling and pronunciation. This is one area, however, where the pronunciation rules are transparent and consistent (although spelling is another matter).

In what follows we are referring to sounds, not spelling so, for example when it is said that the sound at the end of a word like hoped is /t/ that is because that is the sound of the ending -ed and when it is said that the sound at the end of laugh is /f/ that is because it is the sound we are interested in, not the spelling, which happens to be gh.

What follows applies to all of the -s or -es inflexions, to wit:

The regular plural of nouns. For example:
    match-matches
    cut-cuts
    computer-computers
    screen-screens
    boy-boys
and so on.
The Saxon genitive 's ending denoting possession, description, attribute and origin mostly. For example:
    My friend's email
    The battle's consequences
    The woman's kiss
    John's house
    The men's work
    The classes' teachers
etc.
The third-person -s or -es ending on the present simple tense of verbs. For example:
    Mary studies at university
    She puts the car in for a service regularly
    It breaks easily
The contraction of has or is to 's. For example:
She's been to the States
That's my pen
etc.
The contraction of has is slightly irregularly pronounced: see below.

The -s or -es ending is pronounced in three ways, all dependent on the sound at the end of the word to which it is attached.
There is, in fact a good reason for this stemming from what is called regressive assimilation in English. For more on the rules concerning assimilation generally, see the guide to connected speech, linked below.

Here are the rules with some examples.
You'll need to understand some of the phonemic symbols and there's a key to them following the diagrams.

The contraction of has to 's is not pronounced as /ɪz/ but usually as /əz/ as in, e.g.:
The judge's decided (/dʒə.dʒəz/)
The contraction of is to 's is pronounced as above and sounds uncontracted because /ɪz/ is its normal, full-form pronunciation.
The plural of house is irregular because both the letters s are pronounced as /z/ in the plural only.

Key:
The sound /ɪz/ is what you hear when you say fizz, his, Liz etc. It is a short i-vowel followed by the usual sound of the letter z.
The /s/ sound is the usual sound of the letter s and sometimes of the letter c. It is what you hear when you say mouse, soup, lace etc.
The sound /z/ is the same without the vowel as in the beginning of zoo, and in pizzazz, bizarre etc.
The symbol /ʒ/ is the sound represented by the s in leisure and the g in mirage and garage.
The symbol /ʧ/ is the tch sound you hear at the end of hatch, latch, catch and at the beginning of chart, chair, chicken etc.
The symbol /ʃ/ is the sound at the beginning of words like shout, ship, shoot, shop etc.
The symbol /ʤ/ is the sound at the end of budge, fudge and at the beginning and end of judge.

Key:
The /s/ sound is the usual sound of the letter s and sometimes of the letter c. It is what you hear when you say mouse, soup, lace etc.
The /p/ sound is the usual way you say the letter p in pin, pack, stop, hop, pepper etc.
The /t/ sound is the usual way you say the letter t in tin, tack, bat, hot, tatty etc.
The /k/ sound is the usual way you say the letters k, ck or c in kit, cat, tack, back, hock, cake, sack etc.
The /f/ sound is the usual way you say the letters f, ff or ph in fat, fib, different, physics etc. and it is also spelled ugh as at the end of laugh and cough.
The symbol /θ/ is the pronunciation of the th in mouth, path and moth [/maʊθ/, /pɑːθ/, /mɒθ/] but it is softer than the th sound at the beginning of that, this and though [/ðæt/, /ðɪs/, /ðəʊ/] (i.e., /θ/ is unvoiced but /ð/ is voiced).
See the next section for words ending in /θ/ or /ð/ depending on whether they are verbs or nouns.

There are a number of words in English which end with a voiced /ð/ sound when they are verbs (usually with a -e ending) but end with /θ/ if they are nouns. They include:
breathe /briːð/ vs. breath /breθ/
soothe /suːð/ (verb only)
loathe /ləʊð/ (verb only)
bathe /beɪð/ vs. bath /bɑːθ/
clothe /ˈkləʊð/ cloth /klɒθ/
mouth /maʊð/ vs. mouth /maʊθ/
seethe /siːð/ (verb only)
sheathe /ʃiːð/ vs. sheath /ʃiːθ/
teethe /tiːð/ vs teeth /tiːθ/
wreathe /riːð/ vs wreath /riːθ/
writhe /raɪð/ verb only)
These words obey the rules when they take and s ending so, when used as verbs ending in /ð/, the ending is pronounced /z/ and when they are used as nouns ending in /θ/, the s inflexion is pronounced as /s/.

Key:
The sound /z/ is how you pronounce z or zz in the beginning of zoo, and in pizzazz, puzzle, bizarre etc.

This ending serves more than one purpose:

The regular past tense and past participle of verbs, spelled either -d (following an e) or -ed (following other letters). For example:
    smoke-smoked
    cope-coped
    match-matched
    book-booked
and so on.
The ending on adjectives (many of which, but not all, are derived from verbs). For example:
    She's delighted
    They are confused
    The talented children
    The bored audience
    A completed job
etc.

The -d or -ed ending is also pronounced in three ways, all dependent on the sound at the end of the word to which it is attached.

Here are the rules:

Key:
The sound /ɪd/ is what you hear when you say did, lid, fiddle etc. It is a short i-vowel followed by the usual sound of the letter d.
The sound /d/ is the same without the vowel as at the beginning of do, done, dope etc.
The /t/ sound is the usual way you say the letter t in tin, tack, bat, hot, tatty etc.

Key:
The /t/ sound is the usual way you say the letter t in tin, tack, bat, hot, tatty etc.
The /s/ sound is the usual sound of the letter s and sometimes of the letter c. It is what you hear when you say mouse, soup, lace etc.
The /p/ sound is the usual way you say the letter p in pin, pack, stop, hop, pepper etc.
The /f/ sound is the usual way you say the letters f, ff or ph in fat, fib, different, physics etc. and it is also spelled gh as at the end of laugh and cough.
The /k/ sound is the usual way you say the letters k, ck or c in kit, cat, tack, back, hock, cake, sack etc.
The symbol /ʧ/ is the tch sound you hear at the end of hatch, latch, catch and at the beginning of chart, chair, chicken etc.
The symbol /θ/ is the pronunciation of the th in mouth, path and moth [/maʊθ/, /pɑːθ/, /mɒθ/] but it is softer than the th sound at the beginning of that, this and though [/ðæt/, /ðɪs/, /ðəʊ/] (i.e., /θ/ is unvoiced but /ð/ is voiced).
The symbol /ʃ/ is the sound at the end of words like hush, mesh, lash etc.

Key:
The sound /d/ is the same without the vowel as at the beginning of do, done, dope etc.
The voiced consonants are:
/b/ as in sob
/dʒ/ as in hedge
/v/ as in love
/z/ as in amaze
/ɡ/ as in flag
/d/ as in raid
/ð/ as in teethe
/ʒ/ as in massage.
See above for words ending in /θ/ or /ð/ depending on whether they are verbs or nouns. Past tenses of verbs ending in /ð/ follow this rule.

Notes on spelling

It is, of course, pronunciation which drives spelling in the case of noun and verb inflexions. There are exceptions (e.g., the verbs do, have and go as well as some nouns) but the rules are quite simple.

Spelling the -s, -es and 's (and s') endings.
Verbs and pluralised nouns follow the same rules:
1. When the ending is pronounced /ɪz/, it is spelled with -es unless the base form ends in -e, when we only need to add -s. So we get
      choose-chooses
      catch-catches
      push-pushes
      house-houses
      dish-dishes
      pitch-pitches
  etc.
2. When the ending is pronounced /z/ or /s/, the spelling is to add -s so we get
      fall-falls
      sell-sells
      cut-cuts
      lop-lops
      hat-hats
      boy-boys
      speaker-speakers
  etc.
3. The possessive 's and s' endings are slightly variable.
  1. After a singular noun, the possessive 's follows:
    the man's sister
    the car's behaviour
    etc.
  2. If the word has the plural -s or -es ending, then the apostrophe follows the final s of the word so we get:
    the boys' sisters
    the restaurants' menus
    etc.
  3. If the plural is irregular and does not end with s, then we use 's after it.
    the children's toys
    the women's meeting
    etc.
  4. If the singular of a noun already ends in -s then spelling and pronunciation is somewhat idiomatic.
    1. Some fixed expressions with sake only take an apostrophe and pronunciation is unaltered:
          for goodness' sake
          for old times' sake
          for conscience' sake
      etc.
    2. Proper names ending in s usually take only the apostrophe but some spell them and pronounce them with an extra s or /ɪz/ so we get
          James' car (pronounced as /dʒeɪmz.kɑː/)
      or
          James's car (pronounced as /dʒeɪmz.ɪz.kɑː/)
          the class' teacher (pronounced as /klɑːs.ˈtiː.tʃə/ or as /ˈklɑː.sɪz.ˈtiː.tʃə/)
      or
          the class's teacher (pronounced as /ˈklɑː.sɪz.ˈtiː.tʃə/)
Spelling the -ed ending applies to verbs only and is very simple and independent of how the resulting word is pronounced:
We add -d to verbs ending in -e and -ed for everything else so we get:
    allow-allowed
    hate-hated
    water-watered
    delight-delighted
    scare-scared
    offend-offended
etc.
y to i mutation for verbs and nouns.
1. If the base ends in a consonant + y, we change y to i and insert -es or -ed thereafter. We get, therefore:
      comply-complies
      deny-denies
      verify-verified
      weary-wearied
      berry-berries
      activity-activities
      spy-spies
  etc.
2. Proper names do not follow the rules and simple add -s to the name, for example:
      the three Marys who work in my office
      The Davys are coming to dinner
      the Julys of every year
3. If the word ends in a vowel plus y we make no change. So we get
      pay-pays
      delay-delays
      employ-employed
      dismay-dismayed
      day-days
      donkey-donkeys
      way-ways
  etc.
  The verbs lay, pay and say are irregular in respect of tense forms so we get:
      lay-laid
      pay-paid
      say-said (with a change to the pronunciation of the vowel)
  and the exceptions are carried over to the verbs with prefixes as in
      mislay-mislaid
      repay-repaid
  These verbs are regular when taking the -s inflexion
      lays
      pays
      says
  Nouns are regular in this respect, forming plurals without changing y to i.

Related guides
the diagrams	for a PDF document with the diagrams used in this guide
phonology	for an overview of the essentials of phonology
spelling	for more on spelling rules in English
connected speech	this is the in-service guide which explains the rules of assimilation
transcription course	for a course in learning to transcribe the sounds of English phonemically
initial-plus pronunciation index	for other guides to pronunciation issues
in-service pronunciation index	for more technical (and longer) guides to specific areas