Page 10 - Developmental Norms

Important Take-Aways from These Decades of Research on Speech
Acquisition Data

New speech acquisi on data challenges some long‐held beliefs about how and when sounds emerge. Results suggests that
developmental norms are common across all languages, ini al sounds develop as early as age 2, and the majority of sounds are
mastered by age 5, including the American /r/.

We sat down with Dr. Sharynne McLeod of Charles Sturt University in Bathurst, Australia and had a lively conversa on about the
results of the cumula ve research she has led and been part of. Here is a quick recap and four take‐aways from the conversa on.
Dr. Sharynne McLeod is so easy to listen to and her humility is pervasive in everything she shares. If you are new to her work,
there are some things we don't want to skip past: Her work spans decades. She received funding and traveled extensively to the
countries of many of the languages she studied. She purchased and explored oodles of evalua ons tools in mul ple languages to
understand the norma ve data on which they are based. Her country is her lab: The people working with and for her are out in
the rural communi es, towns, and urban centers of Australia.

And what is the result? Possibly the greatest data set accumulated on speech acquisi on. Here are four ideas that can have an
immediate impact on your work.

1. Children are able to produce almost every consonant in their language by age 5.
2. Developmental norms are similar across all languages.

3. Ini al sounds may develop at a younger age than expected.
4. The American English /r/ develops earlier than what has been cited in the literature and is the same as other languages.

American Speech Acquisition Data

There was a point during our conversa on where Dr. McLeod shared that American developmental norms are not necessarily
published in journals but are instead published in test manuals. This led to their follow‐up study in 2020 where they focused
exclusively on American English (Crowe, K., & McLeod, S. (2020), redrawing the lines as to when the English /r/ is
expected to come in.

Several poster downloads were created to easily display the data and are available on the Charles Sturt University Speech
Acquisi on page (h ps://www.csu.edu.au/research/mul lingual‐speech/speech‐acquisi on). Comparing the interna onal data
set and the English data sets, the outlying /th/ sound is the major difference between languages. It should also be noted that most
US norms begin at age three and the compila on of the numerous speech acquisi on data studies showed that the first sounds
occur earlier.

Watch at: h ps://bilinguis cs.com/a‐summary‐of‐current‐speech‐acquisi on‐data‐across‐27‐languages/

Find more great resources at www.bilinguis cs.com. Copyright 2019 10