Substitution

1.Voicing

Children often change the voicing of consonants. Typically children tend to voice consonants that are in the beginning of a word and devoice consonant that are at the end of a word. 

For example:

2. Fronting

Sometimes children bring the place of articulation to the front. This is known as 'fronting.' For example, a child might substitute a velar sound (e.g. /k/), which is produced with the back part of the tongue, with a sound that is produced with their teeth (e.g. [t]).

For example:

3. Substitution of a Liquid for a Glide

This particular type of substitution is actually a key characteristic many people think about when they think of 'baby talk'. This is when a child substitutes a liquid sound (e.g. /l/, /r/) for a glide ([w], [y]). 

For example:

4. Substituting a Fricative with a Stop

Children will often substitute fricatives (e.g. /f/, /v/, /s/) with stops (e.g. /t/, /d/, /p/).  This is attributed to the fact that in most cases stops are the first speech sounds to develop (in English learning children).

For example: