Size sound symbolism in infant-directed speech

The study in a sentence

Six-month old babies may understand something about the size of an object from the pitch of a speaker's voice when talking about it, and previous research suggests that this possible relationship between pitch and size could help with word-learning.

This study aimed to find out whether this size-sound relationship is present in the speech of mothers when interacting with their children. The results only found a pitch-size relationship in the mothers' speech when the size contrast was highly transparent, so it is unlikely to help babies learn associations between pitch and size.

A sample poster used for Stimuli 1 in the study; it is a photograph of a set of objects which vary in size and colour, including a large green chair and a small red bus.

Figure 1: A sample poster used for Stimuli 1 in the study.

The question

Size-sound symbolism is the idea that there is a relationship between the size of something and a linguistic property, e.g. an association between smaller objects and higher pitch. The main question was whether English-speaking mothers would use size sound symbolism when talking about objects in infant-directed speech.

The research focussed on the pitch of speech: would mothers use higher pitch when talking about smaller objects, and lower pitch when talking about larger objects? The study also looked to see if expectations about size (a small version of something large, e.g. a baby elephant) influence size-sound symbolism in mothers' speech.

Key concept

Size-sound symbolism: A systematic relationship between a linguistic property and the size of an object.

Research questions

Do mothers encode size sound symbolic properties in speech addressed to their infants?

Do size expectations about an object affect this sound symbolic encoding?

Methods

This study was conducted during the Covid-19 pandemic, so was run remotely rather than in a lab. The researchers recruited 40 mother-infant pairs to take part, and all the infants were between 14-16 months old.

Participants were sent a poster and two books, and recorded themselves on their phones while looking through the books with their children at home. The researchers then analysed the speech to assess whether stressed vowels in a set of target words used higher or lower pitch depending on the size of the object being described.

The answer

The researchers did not find a reliable link between the size of objects and the pitch at which the mothers talked about that object with their children.
- The link was present when there was a clear size contrast (for example, a picture of a large tiger next to a very small tiger), but not beyond that.
- Expectations about size also did not significantly affect the results.
The study suggests size-sound symbolism is probably not useful for children in learning object words generally.
- The pitch~size effects observed in direct comparison cases suggests that size-sound symbolism may be a useful cue for children in some contexts.

Classroom activities

Lead in task

Noticing size sound symbolism in your own speech

Extension task

Thinking through the design of an experimental study

In more detail

Workshop talk (video) [will be posted a few weeks after the workshop]

Workshop talk (slides) [coming soon]

Meet the author

Catherine Laing

Catherine is a Senior Lecturer whose research focuses on how babies learn and produce their first words. She teaches modules in Bilingualism and Phonological Development.

Read the paper

Laing, C., Khattab, G., Sloggett, S., & Keren-Portnoy, T. (2025). Size sound symbolism in mothers’ speech to their infants. Journal of Child Language, 52(4), 739-761.[DOWNLOAD HERE]

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