How do babies and toddlers choose their first words?

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As a speech pathologist, I’m probably a bit biased. But watching a typical child’s language and speech sound systems blossom is – truly – a wonder to behold.

When magic happens: first words

Language and speech sounds are not the same thing. Babies and toddlers can babble meaninglessly. They can also communicate specific messages in detail without speech, e.g. with gestures. But speech and language come together when kids begin to connect their speech sounds with words they want to say.

For most parents and other carers, this is a pretty special time. I still remember the golden moment when my first child said “dadda” (/daedə/) – and seemed to mean me!

Apart from the memories, first (and later) words matter because vocabulary size is a good indicator of overall language development. Larger vocabulary sizes also correlate with greater phonological (speech sound) skills. Early symptoms of developmental language disorders, include late talking (Hagan et al., 2008). In particular, a lack of word combinations at 24 months is a significant predictor of language impairment (Rudolph & Leonard, 2016).

So how do language and speech come together to produce first words?


Most young children say their first word between the ages of 12 and 18 months. About 6 months after a child says her first word, she can usually say around 50 words; and by 4 years of age, she can typically say around 2,500-3000 words (Fenson et al., 2007; Stoel-Gammon, 2011). These are of course averages: there is huge individual variation in vocabulary sizes for 1 year olds and toddlers (Fenson et al., 2000).

Speech sounds

Kids practice making speech sounds with babble. By 12 months of age, many English-speaking kids can say the following sounds at the start of babbled syllables and/or words:

  • some sounds made by pressing the lips together (e.g. /b/ and /m/). These are called bilabial sounds;
  • some sounds made with the tongue up on the “alveolar ridge” behind the top teeth (e.g. /d/ and /n/). These are called alveolar sounds;
  • some sounds made at the back of the mouth (e.g. /g/ and /h/). These are called “velar” and “glottal sounds”; and
  • a range of vowels (Robb & Bleile, 1994).

Most utterances at this age (words and non-words) are only one syllable long or repeated syllables (Bauman-Waengler, 2000); and many toddlers leave the last consonant off words ending in consonants (“final consonant deletion”) (Davis et al., 2017). Mistakes are common: only about 70% of a typically developing 2-year-olds’ consonants are correct (Stoel-Gannon, 1987).

Fast forward a bit. By 4 years of age, most typically developing English-speaking kids are generally intelligible to unfamiliar adults, and can say:

  • all vowels;
  • almost all consonants at the start and end of words (common exceptions include /s/, /r/, “th” as in thin, and “th” as in “this”);
  • lots of “clusters” of consonants (e.g. /tw, kw, sp, st, bl/ etc.); and
  • one, two and three syllable words (e.g. Smit el al., 1990; Shriberg, 1993).

As with language, there is a high degree of variation in the number of speech sounds spoken by individuals, as well as the order in which speech sounds are acquired (see here for more detail).

So how do babies and toddlers choose their first words?

We don’t know!

There are scores of theories, many with cartoonishly-long academic names. But, broadly, most theories describe one of two main ideas:

  1. Children choose words to say based on the sounds and syllables structures they are capable of saying. This explains why so many kids start with one- or two-syllable words starting with bilabial or alveolar speech sounds, like “mama”, “baby”, “ball” and (yes) “dadda”. We’ll call this the “speech sound dominance theory”.
  1. Children choose words to say based on – um – the words they want to say! For example, a child might attempt “cookie” even though she can’t say /k/ or two-syllable words, because it describes something she really wants. Or she might say “no” first for the simple reason that many toddlers love to communicate rejection with a (screamed) “no” . We’ll call this the “word dominance theory”.

Having read some of the research going back to the ground-breaking work of Leonard in the early 1980s, I favour the speech sound dominance theory. Clinically, it helps me to explain to parents why:

  • so many kids show a preference for words starting with bilabial and alveolar speech sounds across many languages;
  • so many first words are simple consonant-vowel and consonant-vowel-consonant-vowel combinations (e.g. “ma”, “ba”, “mama”, “dadda”);
  • some late-talkers respond well to treatment that focuses on words starting with sounds they can say (so-called “phonological flooding”); and
  • final consonant deletion is so common with toddlers’ speech.

But, as with many things speech science-related, it pays to keep an open mind.

New research

On first reading, a small, recent US study of six children (aged 8 months to 2 years, 11 months) appears to lend further support to the speech sound dominance theory. But, on a closer reading, it suggests that the answer is not clear cut. (See citation below.)

Professor Barbara Davis and colleagues of the University of Texas at Austin found that, overall, the kids favoured words that started with a sound they could say. For kids with small vocabularies, there was some evidence for the word dominance theory in sounds at the ends of words. However, this finding was complicated by the tendency of young children to leave out final consonants: together, the kids in the study left out 63% of the final consonants in target words ending with a consonant!

Clinical bottom line

I’m not changing my mind for now: I still favour the speech sound dominance theory from a clinical perspective. But, having read Davis’ research, I now appreciate that the interaction between language and speech sounds is complex and may go both ways when it comes to first words. As the researchers note, there is plenty of exciting research still to do on this important topic!

Related articles:

Principal source:

Davis, B., van der Feest, S., & Yi, H. (2017). Speech sound characteristics of early words: influence of phonological functions across vocabulary development. Journal of Child Language, 2017. Published online: 4 December 2017.


Man wearing glasses and a suit, standing in front of a bay

Hi there, I’m David Kinnane.

Principal Speech Pathologist, Banter Speech & Language

Our talented team of certified practising speech pathologists provide unhurried, personalised and evidence-based speech pathology care to children and adults in the Inner West of Sydney and beyond, both in our clinic and via telehealth.

David Kinnane
Speech-Language Pathologist. Lawyer. Father. Reader. Writer. Speaker.

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