Residual Speech Errors: Why R and S Errors Last, and What Helps

✓ Reviewed against Flipsen (2015), McAllister et al. (2026) RCT, Preston et al. (2026) RCT, ASHA Practice PortalEvidence level ALast reviewed October 14, 2026Published October 14, 2026

Residual speech errors are sound errors — usually distortions, like a distorted R or S — that last past about age 9. An estimated 1–2% of young adults have them. Up to 75% may resolve by the end of high school, yet treatment helps: in a 2026 trial of 108 children aged 9–15, adding visual biofeedback sped up R learning.

What counts as a residual error

A 2015 review puts the end of the developmental period for speech sounds at about age 9. Errors still present after that come in two kinds: residual errors, the more common type, which began as omissions or substitutions in an earlier speech delay and migrated closer to normal until they became distortions; and persistent errors, which were distortions from an early age and reflect long-held habits.¹

The typical examples are a distorted R — common in American English — and a distorted S or Z. ASHA’s Practice Portal estimates 1% to 2% of young adults show residual or persistent speech errors.^7,8,2

1–2%of young adults have residual or persistent speech errors (Flipsen, 2015; ASHA).^1,2

Residual distortions are a different group from children whose speech sound disorder involves broader errors. A UK population study that deliberately set aside children with only common clinical distortions still found persistent speech sound disorder in 3.6% of 8-year-olds.⁹

Do they resolve?

Often, but slowly. The review estimates that up to 75% of these errors may resolve on their own between about age 9 and the end of high school — while stressing that treatment may still be justified to reduce negative social consequences. Whether residual or persistent errors are more likely to resolve is not clear.¹

The social side is real. A survey of parents of children in treatment for R errors found that children with residual errors face an increased risk of social, emotional, and/or academic challenges compared with peers, though the impact varies widely from child to child.³

What helps

Treatment evidence for residual errors.
Approach	What it involves	Evidence
Motor-based treatment	Cues for tongue placement, shaping from nearby sounds, and specific feedback, following motor-learning principles	Clinical tutorial for /r/; both arms improved in a 2026 trial
Ultrasound biofeedback	A live image of the tongue during speech	Faster early learning and more generalization than motor-based treatment alone in a 108-child trial
Visual-acoustic biofeedback	A live display of the sound’s acoustic pattern	Faster early learning in the same trial; in a 7-child study, 3 children gained more within biofeedback sessions
Short structured drill for S and Z	Placement cues, then concentrated drill moving to natural words	Once-weekly 10-minute sessions produced significant gains in 18 children aged 6;9–11;10; most kept them two years later

Treatment evidence for residual errors.^7,4,5,6,8

The 2026 trial randomly assigned 108 children aged 9–15 with residual R errors to motor-based treatment with or without visual biofeedback. Both groups made progress, but biofeedback produced faster gains in the first sessions and, after 19 sessions, greater accuracy on untreated words; the generalization advantage for ultrasound over visual-acoustic biofeedback was strongest at one site.^4,5

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Next steps for older children and teens

Ask the school SLP about an evaluation — residual errors are treatable at any age.
Ask whether biofeedback is part of the plan if R has not moved with standard practice.
Expect practice to include self-monitoring: noticing and correcting errors in everyday talk.

Find a certified speech-language pathologist through ASHA’s ProFind directory.¹⁰

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About SpeechStep

SpeechStep’s practice is built for ages 4–8. Its instant AI check covers R, but it is not biofeedback and was not designed for teens with long-standing errors — for them, an SLP is the right starting point.

Frequently asked questions

What are residual speech errors?＋

Speech sound errors that remain after the developmental period ends, around age 9. A 2015 review describes residual errors as leftovers of an earlier speech delay that started as omissions or substitutions and moved closer to normal, becoming distortions.

What is the difference between residual and persistent speech errors?＋

In the same review, residual errors (the more common type) are leftovers of an earlier delay, while persistent errors are distortions present from an early age that reflect long-held habits. Whether the two respond differently to treatment is not yet clear.

Do residual speech errors go away on their own?＋

Many do. The review estimates up to 75% may resolve between about age 9 and the end of high school — while noting treatment may still be justified to reduce negative social consequences. About 1–2% of young adults still have them.

What is the best treatment for a residual R error?＋

Motor-based treatment helps, and adding visual biofeedback may help more. In a randomized trial of 108 children aged 9–15 with residual R errors, both groups improved, but children receiving ultrasound or visual-acoustic biofeedback progressed faster early on and generalized more to untreated words.