Speech Sound Development 

Speech Milestones


Phonological patterns disappearing by:
3 years: unstressed syllable deletion, final consonant deletion, diminutization, velar fronting, consonant assimilation, reduplication, prevocalic voicing
4 years: fronting of initial velar singles, deaffrication, cluster reduction w/o “s”
5 years: depalatalization of final singles, depalatalization of initial singles, alveolarization, final consonant devoicing, cluster reduction with “s”
6 years: initial voicing
7 years: gliding of initial liquids
8 years: epenthesis
 
Intelligibility levels:
  19-24 months: 25%-50%
  2-3 years: 50%-75%
  4-5 years: 75%-90%
 5+ years: 90%-100%

Speech Resources