Types of Speech Sound Errors: Omissions, Substitutions, Distortions, Additions
Speech sound errors come in four basic types: omissions (“bu” for “bus”), substitutions (“wabbit” for “rabbit”), distortions (a slushy, lateral S), and additions (“buh-lack” for “black”). ASHA adds weak-syllable deletion and inconsistent whole-word errors. Knowing the type helps you read an SLP report.
The types of speech sound errors
ASHA’s Practice Portal lists the signs of speech sound disorders by error type. The first four are often remembered as SODA: substitutions, omissions, distortions, additions.1
| Error type | What happens | Example |
|---|---|---|
| Omission (deletion) | A sound is left out | “cuh” for “cup”; “poon” for “spoon” |
| Substitution | One sound replaces another, sometimes losing a contrast | “thing” for “sing”; “wabbit” for “rabbit” |
| Distortion | A sound is altered so it is not a clear English sound | A lateral (slushy) S |
| Addition | An extra sound is inserted | “buh-lack” for “black” |
| Syllable-level error | A weak syllable is deleted | “tefone” for “telephone” |
| Inconsistent whole-word error | The same word comes out differently each time, without motor difficulty | “strawberry” said three different ways |
Speech sound error types (ASHA Practice Portal).1
Single errors vs. patterns
ASHA notes that errors may occur as independent articulation errors and/or as phonological, rule-based patterns. A child may also substitute one favorite sound for many others, producing several homonyms — “shore,” “sore,” “chore,” and “tore” might all come out the same.1
Named patterns are mostly organized substitutions and omissions: fronting replaces back sounds with front ones (“tat” for “cat”), stopping replaces fricatives with stops (“pun” for “fun”), gliding replaces L and R with W or Y, and final-consonant deletion drops the last sound (“bu” for “bus”).3
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What the error type tells you
- Substitutions and omissions in young children are often developmental patterns that fade on a typical timetable.
- Distortions point to how a sound is physically made — a lisp is the classic example.
- Inconsistent whole-word errors suggest a different kind of difficulty and need an SLP’s assessment.
- Errors that make a child hard to understand matter more than errors on late sounds.
MedlinePlus gives everyday examples: an articulation disorder might sound like “coo” for “school” or a whistled S, while a phonological disorder might drop or change the first or last sounds of words, such as “boo” for “book.”2
Frequently asked questions
What are the four types of speech sound errors?＋
Omissions (a sound left out), substitutions (one sound replaced by another), distortions (a sound altered so it is not quite any English sound, such as a lateral S), and additions (an extra sound inserted). Clinicians often remember them as SODA.
What is a distortion error?＋
A sound that is altered or changed rather than replaced by another clear sound. ASHA’s example is a lateral /s/, where air escapes over the sides of the tongue so the S sounds wet or slushy.
What is the difference between a substitution and a phonological pattern?＋
A substitution is one sound replaced by another. When substitutions follow a rule across many sounds — every back sound replaced by a front sound, as in fronting — clinicians call it a phonological pattern. ASHA notes errors can be independent articulation errors and/or rule-based patterns.
Which errors are most serious?＋
It depends on age and pattern, not just type. Errors that are inconsistent from one try to the next, unusual patterns, and errors that make speech hard for others to understand all deserve an SLP evaluation.
Put this into practice today
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References
3 sources from authoritative bodies. Last reviewed October 2026.
- 1.ASHASpeech Sound Disorders: Articulation and Phonology — Practice Portal page.
- 2.MedlinePlus (U.S. National Library of Medicine)Speech disorders - children — Medical encyclopedia.
- 3.ASHASelected Phonological Patterns — Practice Portal page.