Phonological process
Stopping
Stopping is a phonological process in which a child replaces a fricative or affricate — a continuous, airflow-based sound like /s/, /f/, or /ʃ/ — with a stop consonant such as /t/, /p/, or /d/, so "sun" becomes "tun" and "fish" becomes "pit". Unlike most processes it does not have a single resolution age: it resolves sound by sound, from around age 3 for /f/ to around age 5 for "th".
In plain English
Fricatives require holding a narrow gap and keeping air flowing through it for a sustained moment. Stops just require closing and releasing. A child who has not yet learned to maintain that controlled turbulence defaults to the closure they can already make.
Examples
| Word | Target | Typical production |
|---|---|---|
| sun | /s ʌ n/ | "tun" — /t ʌ n/ |
| zoo | /z uː/ | "doo" — /d uː/ |
| fish | /f ɪ ʃ/ | "pit" — /p ɪ t/ |
| chair | /tʃ ɛ ɹ/ | "tair" — /t ɛ ɹ/ |
| van | /v æ n/ | "ban" — /b æ n/ |
When it typically resolves
Stopping typically resolves sound by sound, from about age 3 to about age 5.
Why it happens
- Stops are among the earliest consonants children produce, appearing in babbling long before fricatives do, so they are the available fallback when a fricative is attempted.
- Producing a fricative requires forming and holding a precise constriction while regulating breath pressure across it — an aerodynamic control problem, not just a placement problem.
- Different fricatives resolve at different ages because they differ in difficulty: /f/ is visible on the lip and easy to cue, while /θ/ and /ð/ require an interdental placement that many languages do not even contain.
- Some children stop only the later-developing fricatives while producing /f/ correctly, which is why stopping should always be described per sound rather than as a single all-or-nothing pattern.
When it is a concern
- The specific sound being stopped is past its own typical resolution age — /f/ still stopped at 4, for example, is more concerning than "th" still stopped at 4.
- Stopping applies broadly across the whole fricative class rather than to a couple of late sounds.
- It combines with other patterns to reduce intelligibility below what is expected for the child's age.
- Stopping of nasals or of /h/, which is not part of the typical developmental pattern, is a reason to seek evaluation regardless of age.
How clinicians treat it
- Cycles approach, which targets several phonological patterns in rotation over a period of weeks, is frequently used when stopping appears alongside other processes.
- Auditory bombardment — the child listens to many amplified productions of the target sound class before attempting production.
- Minimal pairs contrasting the stop and the fricative ("sea/tea", "fan/pan", "sue/two").
- Prolongation cueing: eliciting a long, sustained /sssss/ or /fffff/ in isolation first, so the child experiences the continuous airflow before it has to be timed inside a word.
How ArticScore detects it
- Stopping produces a large acoustic difference — a burst where sustained frication was expected — which makes it one of the more visible error types to a phoneme-level acoustic model.
- ArticScore returns a per-phone score in word context, so an app can see that the /s/ in "sun" scored low while the /s/ in "bus" scored well, which is exactly the position-specific detail an SLP would want in a summary.
- Because stopping resolves sound by sound, the useful product behaviour is per-phoneme reporting rather than a single word score — which is the reason ArticScore returns phoneme rows at all.
Stopping — questions
What is stopping in speech therapy?
Stopping is when a child replaces a fricative or affricate — a sound made with continuous airflow, like /s/, /f/, /v/, or /sh/ — with a stop consonant like /t/, /d/, or /p/. "Sun" becomes "tun" and "fish" becomes "pit".
At what age should stopping stop?
There is no single age, because stopping resolves sound by sound. Commonly cited norms put /f/ and /s/ at about age 3 to 3;6, /v/ and /z/ at about 3;6, /sh/, /ch/ and /j/ at about 4;6, and "th" at about 5;0. Judge each sound against its own norm rather than against a single cutoff.
Is stopping the same as a substitution error?
Stopping is a kind of substitution, but the term describes a pattern rather than a single error. If a child substitutes /t/ for /s/ once it is a substitution; if the child systematically replaces the whole fricative class with stops, clinicians describe that pattern as stopping, and treat the pattern rather than each sound in isolation.
How does automatic pronunciation scoring handle stopping?
Stopping is comparatively visible to an acoustic model because a stop burst and a fricative look very different in the signal. A phoneme-level scorer will typically score the fricative target low and identify the stop it heard instead. Our own evaluation caveat still applies: the number of labelled examples behind any per-category figure is small, so treat category-level rates as indicative.