This document provides a chart describing typical phonological process development in children. It includes substitution, syllable structure, and assimilation processes. Substitution processes involve replacing one type of sound with another, such as stopping where fricatives are replaced with stops. Syllable structure processes modify word structure, like unstressed syllable deletion. Assimilation occurs when sounds change to become more like neighboring sounds, as in labial assimilation where sounds become labialized. The chart lists examples and average ages each process is typically outgrown by.

1. TYPICAL PHONOLOGICAL PROCESS DEVELOPMENT CHART
Substitution Processes - when one class of sounds is replaced for another
class of sounds.
Phonological
Process
What is
Happening?
Examples Gone by Age
Stopping
(Stop)
When a child
substitutes
a stop (b, p,
d,
t, g, k)
for a fricative
(s, z, f, v,
th’s, h,
sh,and zh
as in
measure)
/pat/ for fat 3 yrs.
/pine/ for vine 3 1/2 yrs.
/tear/ for chair 4 1/2 yrs.
/dob/ for job 4 1/2 yrs.
/take/ for shake 4 1/2 yrs.
/tope/ for soap 3 yrs.
/pum/ for thumb 5 yrs.
Deaffrication
When a child
replaces an
affricate
(ch, dz as in
judge)
with a
stop (b, p, d,
t, g, k)
or a
fricative (s, z,
f, v,th’s, h,
sh,
and zh as in
measure)
/tear/ for chair
Not
Available
/sop/ for chop
/karm/ for charm
/dob/ for job
/dim/ for gym
/zan/ for Jan
Velar Fronting When a child /top/ for cop 3 1/2 yrs.

2. (VF) replaces a
velar sound
(k, g, ng)
with a sound
that is made
toward the
front of the
mouth.
Fronting
usually
happens more
often in the
beginning of
words
compared to
the end
/reen/ for ring 3 1/2 yrs.
/tup/ for cup 3 1/2 yrs.
/doh/ for go 3 1/2 yrs.
/tum/ for gum 3 1/2 yrs.
Depalatalization
(Dep)
When a child
substitutes
an alveolar
fricative
(s, z) for a
palatal
fricative
(sh, and zh
as in
measure)
/tek/ for check
Not
Available
/matsiz/ for
matches
/dudz/ for judge
/dane/ for Jane
Backing
*This occurs in
children with severe
phonological
disorders.
When a child
substitutes a
front sound
(t, d) with a
back sound
(k, g)
/kop/ for top
Not
Available
/hope/ for soap
/gime/ for dime
/bike/ for bite
Liquid Gliding
(LG)
When a child
substitutes a
/wabbit/ for
rabbit
5 yrs.

3. glide sound
(w, y) for a
liquid sound
(r, l)
/wook/ for look
/wing/ for ring 5 yrs.
/yeef/ for leaf
This can also
occur in
consonant
clusters
/bwed/ for bread 5 yrs.
/gween/ for
green
5 yrs.
/bwack/ for
black
/gwas/ for glass
Vocalization
(Voc)
This is also
known as
vowelization
and happens
when a child
substitutes a
vowel for a
syllabic
liquid
/simpo/ for
simple
Not Available
/abuh/ for able
/tabo/ for table
/papo/ for paper
Syllable Structure Processes – sound changes that modify the syllabic
structure of words.
Phonological
Process
What is
Happening?
Examples Gone by Age
Unstressed
Syllable
Deletion (USD)
When a child
doesn’t say
the syllable
with the least
amount of
stress
/medo/ for
tomato
4 yrs.
/tefon/ for
telephone
4 yrs.
/efant/ for
elephant
4 yrs.
/nana/ for 4 yrs.

4. banana
/side/ for outside 4 yrs.
Reduplication
(Redup)
When a child
repeats a
syllable of a
target word
which creates
a multi-
syllabic word
form.
Reduplication
can be Total
or Partial
Total
/baba/ for bottle 2 1/2 yrs.
/dada/ for dog 2 1/2 yrs.
/tata/ for
television
2 1/2 yrs.
Partial
/bada/ for bottle 2 1/2 yrs.
/dadi/ for dog 2 1/2 yrs.
/tatu/ for
television
2 1/2 yrs.
Dimunization
(Dim)
When a child
adds an “-ee”
and
sometimes a
consonant +
“-ee” to a
target word.
/cup-ee/ for cup
Not Available
/book-ee/ for
book
/doll-ee/ for doll
Epenthesis
When a child
says an
unstressed
vowel usually
“uh” between
two
consonants.
/suh-poon/ for
spoon
Not Available/cup-uh/ for cup
/puh-late/ for
plate
Final-
Consonant
When a child
leaves a
Open
/ma/ for mom 3 yrs. 3 mos.

5. Deletion (FCD) single
consonant or
consonant
cluster off of
the end of a
word.
This can
happen on
words that
end with a
vowel (open-
syllable
word) or on
words that
end in
consonants
(closed-
syllable
word)
/da/ for dog 3 yrs. 3 mos.
/wag-ih/ for
wagon
3 yrs. 3 mos.
Closed
/boo/ for books 3 yrs. 3 mos.
/ha/ for hand 3 yrs. 3 mos.
Initial
Consonant
Deletion (ICD)
*This is more
uncommon but can
occur in children with
severe phonological
disorders.
When a child
does
not say the
first
single
consonant or
consonant
cluster
at the
beginning
of a word.
/own/ for phone
Not Available
/ah-zit/ for
closet
/oo/ for shoe
/indo/ for
window
/op/ for stop
Cluster
Reduction/
Deletion (CR)
or
Cluster
When a child
deletes or
substitutes
some or all
parts of a
Total All Cluster Reduction
and
Substitution should be
gone by
3 1/2 yrs.
/op/ for stop
/eight/ for
straight

6. Substitution cluster.
Cluster
deletion can
be Total or
Partial
/da/ for dark
Partial
Cluster
Substitution
/top/ for stop
/bwed/ for
bread
/tate/ for straight
/pwace/ for
place
/dak/ for dark
Assimilation Processes – one sound changes to become more like another
sound, usually its neighboring sound.
Phonological
Process
What is
Happening?
Examples Gone by Age
Labial
Assimilation
When a
sound is
changed to a
labial sound
(b, p, m, w)
because of
another labial
sound in a
word.
Labial
Assimilation
can be Total
or Partial
/wap/ for wax
Not Available
/peb/ for pen
/mob/ for moss
Total
/bub/ for bug
Partial
/bup/ for bug
Velar
Assimilation
When a non-
velar sound is
/kug/ for cup
Not Available
/keek/ for keep

7. changed to a
velar (k, g,
ng) sound.
Velar
Assimilation
can be Total
or Partial
/goag/ for goat
Total
/kuck/ for cup
Partial
/kug/ for cup
Nasal
Assimilation
When a non-
nasal sound
is changed to
a nasal (m, n,
ng) because
of the
influence of
another nasal
sound in the
word.
Nasal
Assimilation
can be Total
or Partial
/mom/ for mop
Not Available
/nong/ for long
/non/ for nose
Total
/mom/ for mop
Partial
/mon/ for mop
Alveolar
Assimilation
When a non-
alveolar
sound is
changed to an
alveolar
sound (t, d, n,
l, s, z)
/tot/ for toss
Not Available
/suit/ for soup
/dod/ for door
Total
/tot/ for top
Partial
/tod/ for top
Prevocalic When a /den/ for ten Not Available

8. Voicing voiceless
sound that
comes before
a vowel is
changed to a
voiced sound.
/zuit/ for suit
/vight/ for fight
/bie/ for pie
Postvocalic
Devoicing
When a
voiced stop,
fricative, or
affricate, that
follows a
vowel is
changed to a
voiceless
sound
(devoiced)
/pick/ for pig
Not Available
/tuck/ for tug
/sat/ for sad
/bis/ for bees