Your bilingual child doesn't sound quite like their monolingual classmates. That's not a problem to solve — it's the signature of a brain building two (or three, or more) sound systems at once. Each language has its own phonemes, its own rhythm, its own rules for how sounds fit together, and your child is sorting all of that out in parallel.
The single most important thing to know up front: an accent is not a speech disorder. It's the natural result of knowing more than one language. This article walks through how typical bilingual speech sound development actually works. For the follow-up detail on specific patterns — and how to tell a typical pattern from one that needs attention — see our companion article on bilingual speech sound patterns.
How Speech Sound Development Works in Bilingual Children
Every language has its own set of speech sounds (called phonemes) and its own rules about how those sounds can be combined. English, for example, has about 44 phonemes. Cantonese has a different set again. Vietnamese, Arabic, Spanish, Dinka, Hindi — each has its own unique collection. Aboriginal languages, traditional languages of the Torres Strait, and varieties like Aboriginal English and Kriol also have their own sound systems, all of which are equally valuable parts of a child's linguistic identity.
When a child is learning two or more languages, they're building two, three, or more phonological systems — mental maps of how sounds work in each language. Research by McLeod, Verdon, and the International Expert Panel on Multilingual Children's Speech (2017) found that multilingual children develop their speech sounds along broadly predictable paths, but with some important differences from monolingual peers.
Key findings from this large-scale international study include:
- Bilingual and multilingual children may acquire some sounds earlier than monolingual children (particularly sounds that exist across their languages)
- They may acquire other sounds later, especially sounds that are unique to just one of their languages
- Their overall speech sound development is influenced by the amount and type of input they receive in each of their languages
This means that comparing a bilingual or multilingual child directly to monolingual norms can give a misleading picture of their abilities — one of the recurring themes in what the research tells us about bilingual development.
Cross-Linguistic Transfer: When One Language Influences Another
One of the most interesting features of bilingual speech development is something called cross-linguistic transfer. This is when the sound patterns of one language influence how a child produces sounds in the other language.
Goldstein and Fabiano-Smith (2010) studied bilingual Spanish-English children and found that cross-linguistic transfer is a normal and expected part of bilingual development. It can show up in several ways:
- Accent influence. Your child might produce English sounds with the rhythm or intonation patterns of their home language, or vice versa. This is perfectly natural — it's the same thing that happens when adults speak a second language with an accent.
- Sound substitutions. If a sound exists in one language but not the other, your child might substitute a familiar sound from their other language. For example, a child whose home language doesn't have the "th" sound might replace it with "d" or "f" in English — because those sounds are closer to what exists in their home language's sound system.
- Syllable structure differences. Languages have different rules about how syllables are built. A child whose home language tends to end syllables with vowels might drop final consonants in English, because that pattern feels more natural to them.
These transfer patterns are not errors in the traditional sense. They reflect the child's developing understanding of two sound systems and how they relate to each other. Over time, as children get more exposure and practice, many of these patterns resolve on their own.
Across the bilingual children I've assessed, what often looks like a "speech problem" to worried parents turns out to be textbook cross-linguistic transfer — and naming it for families tends to shift the conversation immediately.
What's Typical and Expected
Here are some things that are completely normal in bilingual speech development:
- An accent in one or both languages. Having an accent is not a speech sound difficulty — it's a natural result of speaking more than one language.
- Sound substitutions that reflect the other language. As described above, using sounds from Language A when speaking Language B is a transfer pattern, not a sign of a problem.
- Different levels of speech clarity in each language. Your child may be easier to understand in their dominant language than in their less-used language. This reflects exposure and practice, not ability.
- Slower development of sounds unique to one language. Sounds that only exist in one of your child's languages may take a bit longer to develop, and that's okay.
- Some inconsistency. Bilingual children might produce a sound correctly in one language context but not another. This is part of the process of sorting out two systems.
When to Wonder If It's More Than Typical
Most of what you'll notice in your bilingual child's speech is typical. But some things do warrant a closer look — and the golden rule is simple: a genuine speech sound difficulty shows up across all of a child's languages, not just one. If your child is difficult to understand in both (or all) their languages even by family members, if sound errors don't match the rules of any of their languages, or if their speech isn't progressing over time, it's worth booking an assessment.
We cover the specific patterns to watch for in much more detail — along with a when-to-worry guide — in the companion article on bilingual speech sound patterns.
Don't skip the hearing check. When a child is learning two or more languages, a hearing issue affects how they perceive sounds in all of them. Before chalking anything up to bilingualism, it's worth knowing the ears are doing their job — a paediatric audiologist is the place to start.
Why Assessment Matters
If you're concerned about your bilingual child's speech sounds, a thorough assessment by a speech pathologist who understands bilingual development is essential. A good assessment gathers information about both languages — which sounds exist in each, what patterns are expected, and how much exposure your child gets — and looks at speech in both languages where possible, often with support from family members or interpreters. The goal is to distinguish between transfer patterns (which are typical) and error patterns that genuinely need support, rather than treating every difference as a problem.
At Speaking Speech Pathology, we take the time to understand your child's full linguistic picture before making any judgements about their speech development.
The Bottom Line
Bilingual speech development is complex, fascinating, and — most importantly — normal. Your child's brain is doing incredible work managing two sound systems at once, and some differences from monolingual peers are completely expected. The key is knowing the difference between a bilingual speech pattern (which will typically resolve with time and exposure) and a genuine speech sound difficulty (which will benefit from targeted support).
Ready for practical strategies? Read our companion article: Common Speech Sound Patterns in Bilingual Children: When to Worry | Brisbane
Alexandra Bouwmeester is a Senior Speech Pathologist (MSPA, CPSP) with over 14 years' experience in paediatric speech pathology. She offers culturally responsive mobile speech pathology to families across Brisbane's south side and Logan.
Bilingual speech development is complex and fascinating — and most of the patterns parents worry about are completely typical. If you'd like clarity about your child's speech sounds, Speaking Speech Pathology is always happy to chat.
References
Goldstein, B. A., & Fabiano-Smith, L. (2010). Phonological skills in predominantly English-speaking, predominantly Spanish-speaking, and Spanish–English bilingual children. Language, Speech, and Hearing Services in Schools, 41(3), 273–283.
McLeod, S., Verdon, S., & International Expert Panel on Multilingual Children's Speech. (2017). Tutorial: Speech assessment for multilingual children who do not speak the same language(s) as the speech-language pathologist. American Journal of Speech-Language Pathology, 26(3), 691–708.
McLeod, S., & Crowe, K. (2018). Children's consonant acquisition in 27 languages: A cross-linguistic review. American Journal of Speech-Language Pathology, 27(4), 1546–1571.
