Normative Data Sound System Disorder

3-Year-Olds: Errors Needing Therapy

bulletDeletion of p, b, m, n, d, t, f, h, w, j (y)
bulletVowel Distortions
bulletExamples of Patterns
­ Final Consonant Deletion
­ Initial Consonant Deletion
­ Stopping
­ Glottal Replacement

3-Year-Olds: Developmental*, Errors

bulletUnstressed Syllable Reduction
bulletCluster Reduction
bulletPrevocalic Voicing
bulletDeaffrication (ch -> sh; J -> zh)
bulletGliding Liquids
bulletVocalizing Liquids
bulletFronting Palatals (s -> sh) & Velars (k, g -> t, d)
bulletDental Simplifications (th -> f, d)
bulletv -> b
bulletDental/Lateral Distortion of Sibilants

4-Year-Olds: Errors Needing Therapy

bulletAny consonant deletion
bulletVowel Distortion Deletions
bulletExamples of Additional Patterns
­ Fronting Palatals and Velars
­ Cluster Reduction
­ Syllable Reduction
­ Deaffrication

4-Year-Olds: Developmental Errors

bulletGliding Liquids
bulletVocalizing Liquids
bulletDental Simplifications (f/th, d/th)
bulletb/v
bulletDental/Lateral Distortion of Sibilants

5/6-Year-Olds: Errors Needing Therapy

bulletLateral Distortion of Sibilants

5/6-Year-Olds: Developmental Errors

bulletGliding Liquids
bulletVocalizing Liquids
bulletDental Simplifications (f/th, d/th)
bulletb/v
bulletDental Distortion of Sibilants

7-Year-Olds: Errors Needing Therapy

bulletAny error!
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* These errors may possibly be developmental. However, we can never really be sure by considering only one sample whether maturation will result in spontaneous normalization.