Stopping is a phonological process where a child replaces fricative or affricate sounds (like /f/, /s/, /sh/, /ch/) with stop sounds (like /p/, /t/, /d/). So “soap” becomes “dope,” “fish” becomes “tish,” or “chair” becomes “tare.” It’s one of the most common patterns in early speech development, and in most cases, children outgrow it naturally by age 3 to 5, depending on the specific sound.
How Stopping Works
To understand stopping, it helps to know the difference between the two types of sounds involved. Fricative sounds, like /f/, /s/, /v/, /z/, /sh/, and “th,” are made by pushing air through a narrow gap in the mouth, creating a hissing or buzzing quality. Affricate sounds, like /ch/ and /j/, combine a brief stop with a burst of friction. Both types require precise control of airflow and tongue placement.
Stop sounds, like /p/, /b/, /t/, /d/, /k/, and /g/, are simpler. You briefly block the airflow completely, then release it. Young children default to these easier stop sounds because they haven’t yet developed the motor control needed for the more complex fricatives and affricates. The substitution follows a predictable pattern: voiceless fricatives get replaced by voiceless stops, and voiced fricatives get replaced by voiced stops. That’s why /s/ (voiceless) becomes /t/ (voiceless), and /z/ (voiced) becomes /d/ (voiced).
Common Sound Substitutions
Stopping shows up across a wide range of sounds, but some substitutions are more frequent than others. Here are the most typical ones:
- /s/ becomes /t/: “sun” sounds like “tun,” “sea” sounds like “tea,” “sock” sounds like “tock”
- /f/ becomes /p/: “fish” sounds like “pish,” “fan” sounds like “pan,” “four” sounds like “pour”
- /z/ becomes /d/: “zoo” sounds like “doo”
- /v/ becomes /b/: “very” sounds like “berry”
- /sh/ becomes /t/: “shoe” sounds like “too,” “shop” sounds like “top”
- /ch/ becomes /t/: “chair” sounds like “tare,” “chop” sounds like “top”
- /j/ becomes /d/: “jump” sounds like “dump,” “jam” sounds like “dam”
- “th” becomes /t/ or /d/: “thing” sounds like “ting,” “them” sounds like “dem”
These substitutions can happen at the beginning of words, at the end, or both. A child who stops /s/ might say “tun” for “sun” and “bu-t” for “bus.”
When Children Typically Outgrow It
Not all stopped sounds resolve at the same age. Children drop this pattern in stages, with simpler fricatives clearing up first and more complex ones taking longer:
- By age 3: Stopping of /f/ and /s/ should resolve
- By age 3.5: Stopping of /v/ and /z/ should resolve
- By age 4.5: Stopping of /sh/, /ch/, and /j/ should resolve
- By age 5: Stopping of “th” (both voiced and voiceless) should resolve
This means a 2-year-old saying “tun” for “sun” is developing normally. A 4-year-old doing the same thing is behind the expected timeline. And a 4-year-old who says “ting” for “thing” is still within the normal range, since “th” is the last sound where stopping typically disappears.
How Stopping Affects Speech Clarity
When stopping persists beyond the expected ages, it can significantly reduce how well others understand a child. Research from Portland State University found that stopping was one of the key phonological processes contributing to reduced speech intelligibility in young children, alongside patterns like cluster reduction (dropping sounds from blends like “st” or “bl”). Among children rated as unintelligible by listeners, many used stopping in combination with other processes.
The reason stopping has such a strong effect on clarity is that it collapses many different words into the same sound. If a child replaces both /s/ and /sh/ with /t/, then “sip,” “ship,” and “tip” all sound identical. Listeners lose the ability to distinguish words from context alone, especially in conversation where there aren’t visual cues to help.
Typical Development vs. Phonological Disorder
Stopping on its own doesn’t indicate a disorder. It’s a normal part of how children learn to speak. The distinction between typical development and a phonological disorder comes down to timing and persistence. If a child is still stopping sounds well past the expected elimination ages listed above, a speech-language pathologist may identify it as part of a phonological disorder rather than a simple delay.
Other factors that push the assessment toward a disorder include the number of sounds affected, whether stopping occurs alongside several other phonological processes, and how much the pattern limits the child’s ability to communicate. A child who stops only “th” at age 4.5 is in a very different situation from a child who stops /f/, /s/, /sh/, and /ch/ at the same age.
How Speech Therapy Addresses Stopping
The most widely used technique for treating stopping is called minimal pairs therapy. It works by presenting the child with two words that differ by only one sound, where the child’s substitution creates a different real word. For example, “sea” versus “tea,” or “thick” versus “tick.” The child sees pictures of both words and tries to say the target. If they say “tick” when they mean “thick,” the therapist picks up the wrong picture, creating a clear communication breakdown the child can see and feel.
This approach is effective because it gives the child a concrete reason to change their pronunciation. Rather than drilling sounds in isolation, minimal pairs therapy shows the child that their substitution actually changes the meaning of what they’re saying. The moment they realize that saying “tea” when they mean “sea” gets them the wrong picture, they’re motivated to figure out how to produce the fricative sound.
Therapists typically select one or two target sounds to work on at a time, starting with the sounds that are most developmentally appropriate for the child’s age. Common minimal pair sets used in therapy include “sea/tea,” “sip/tip,” “sail/tail” for /s/ stopping, and “fat/pat,” “fan/pan,” “fin/pin” for /f/ stopping. For “th” stopping, pairs like “thick/tick” and “thought/taught” are standard choices. Parents can reinforce these at home through picture-matching games using the same word pairs.