Abstract
This report reviews the existing literature on the emergence and prevalence of speech
sound errors in older children and adults. Findings from several different sources
suggest that 1 to 2% of the young adult population overall may present with these
errors. Up to 75% of these errors may resolve on their own between the end of the
developmental period (i.e., age 9 years) and the end of high school, though speech
therapy services may still be justified to reduce any negative social consequences
of these errors. At least two different sources of these errors are postulated. Residual
speech errors (the more common of the two types) appear to arise as a leftovers from
a much earlier speech delay and were originally omission or substitution errors but
migrated closer to normal to become distortions. Persistent speech errors, on the
other hand, appear to be distortions from an early age that reflect long-instantiated
habits. Whether this distinction points to different responses to particular interventions,
or whether either type is more or less likely to resolve spontaneously is not clear
at this time.
Keywords
Etiology - prevalence - residual speech error - persistent speech error
