Assimilation (Consonant Harmony): Why Kids Say “Goggy” for “Doggy”

✓ Reviewed against ASHA Selected Phonological Patterns, ASHA Practice PortalEvidence level ALast reviewed October 14, 2026Published October 14, 2026

Assimilation, or consonant harmony, is when one sound in a word changes to match another sound nearby: “goggy” for “doggy,” “kak” for “tack,” “money” for “funny.” It is one of the earliest patterns young children use, and ASHA lists both velar and nasal assimilation as usually gone by about age 3.

What assimilation is

Assimilation — also called consonant harmony — is a phonological process in which one sound in a word becomes the same as, or similar to, another sound in that word. Instead of planning two different consonants, the child repeats one. ASHA lists two common forms with a typical age for each.¹

Common assimilation patterns (ASHA, Selected Phonological Patterns).
Pattern	What happens	Examples	Likely age of elimination
Velar assimilation	A sound becomes K or G because of a K or G nearby	“kak” for “tack,” “guck” for “duck,” “goggy” for “doggy”	about 3
Nasal assimilation	A sound becomes a nasal (M, N) because of a nasal nearby	“money” for “funny,” “nunny” for “bunny”	about 3

Common assimilation patterns (ASHA, Selected Phonological Patterns).¹

The giveaway is that the change depends on the word. A child who says “goggy” for “doggy” may still say “dad” correctly, because there is no G in “dad” to pull the D toward it.

Assimilation vs. fronting and other swaps

Assimilation is easy to confuse with substitution patterns such as fronting. The difference is whether a neighbouring sound is responsible.¹

Assimilation vs. fronting.
	Assimilation	Fronting
Why the sound changes	Another sound in the same word pulls it	A whole class (K, G) is replaced everywhere
Example	“goggy” for “doggy”	“tat” for “cat”
Depends on the word?	Yes	No
Usually gone by about	3	4

Assimilation vs. fronting.¹

When assimilation usually stops

ASHA lists both velar and nasal assimilation as usually gone by about 3 — together with final consonant deletion, the earliest processes on its chart. It fits the sound timetable: the consonants involved (B, D, M, N, then K and G) are among the first acquired, with B, N, M, P, H, W, and D in place by 2;0–2;11 and K and G by 3;0–3;11 at the 90% criterion in US data. Across 27 languages, most consonants are acquired by about 5.^1,3,9

~3the likely age by which velar and nasal assimilation stop (ASHA, Selected Phonological Patterns).¹

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How it is treated, and what helps at home

If assimilation persists, SLPs usually work on it with contrast pairs that make the two consonants in the word matter, and by practicing words where the two sounds differ in steps. ASHA describes minimal pairs as helping to establish contrasts not yet in a child’s sound system, and a 2022 tutorial recommends conventional minimal pairs mainly for children with a small number of errors.^2,4

Model clearly: reply to “goggy” with a warm, slightly slow “Yes, a do-ggy!”
Practice one-consonant words first (“dough,” “go”), then words that mix them (“dog-go”).
Keep it playful and short — a few relaxed repetitions in everyday play.

ASHA’s parent guidance is to give good speech models rather than correcting children’s sounds; it is normal for young children to say some sounds the wrong way while they learn.⁶

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When to get help

ASHA’s rule is that patterns persisting past their usual age, or atypical patterns, lead to a diagnosis of phonological disorder. Because assimilation usually stops by about 3, consistent assimilation in a 4-year-old — especially alongside other patterns or speech that is hard to understand — is a reason to see a speech-language pathologist.^1,5

Learn the milestones and raise concerns with your pediatrician, or find a certified SLP through ASHA’s ProFind directory. Children who have trouble producing speech sounds correctly may have a speech disorder.^7,8,10

Frequently asked questions

What is assimilation in speech?＋

Assimilation — also called consonant harmony — is a phonological process in which one sound in a word becomes the same as, or similar to, another sound in that word. ASHA describes velar assimilation (“kak” for “tack,” “guck” for “duck”) and nasal assimilation (“money” for “funny,” “nunny” for “bunny”).

At what age should assimilation stop?＋

ASHA lists the likely age of elimination for both velar and nasal assimilation as about 3 — among the earliest processes to fade, alongside final consonant deletion.

How is assimilation different from fronting?＋

Assimilation depends on the word: the sound changes because another sound in the same word pulls it (“goggy” — the G in the middle turns the D into G). Fronting is a general swap that happens wherever K and G appear (“tat” for “cat,” whatever else is in the word).

Should I be worried about assimilation in a 4-year-old?＋

It is worth an evaluation. ASHA’s rule is that patterns persisting past their usual age lead to a diagnosis of phonological disorder, and assimilation is expected to be gone by about 3. An SLP can tell whether it is one leftover pattern or part of a bigger picture.