||Evidence for atypical categorical speech perception in Williams syndrome
Although language processing has been described as being a relatively
‘spared’ cognitive function in individuals presenting with
Williams syndrome (7q11.23 microdeletion; WS), some studies
suggest possible alterations at the level of input speech processing.
We explored categorical speech perception and non-speech auditory
perception in six participants with WS, as well as in chronological
age-matched or reading age-matched control groups.
Categorical speech perception was explored for the b-d speech
sound continuum, where speech sounds vary in spectral acoustic
features, and for the d-t speech sound continuum, where speech
sounds vary in temporal acoustic features. Non-speech perception
was explored for sine-wave analogues of the b-d continuum,
which are not identified as speech stimuli. We observed a significantly
increased ability in WS participants to detect subtle acoustic
changes between adjacent stimuli of the b-d or the d-t continuum
outside the phoneme boundary, when control participants showed
absence of discrimination. This is the first study to provide
evidence for an atypical sensitivity towards subtle acoustic variations
during speech and non-speech auditory analysis in WS.
Implications for phonological processing and reading acquisition