Individuals with 16p11.2 Deletions Show Aberrant Feedback Processing during Speaking
Objectives: To examine the impact of auditory feedback processing on speech production in participants with 16p11.2 deletion compared to sibling controls.
Methods: Two tests of sensitivity to auditory feedback during speech were collected from 12 participants with 16p11.2 deletion and six sibling control participants. The first test, called a pitch perturbation test, examined how subjects quickly changed the pitch of their voice within a trial to correct for a brief perturbation of their auditory feedback, a response known as “pitch feedback compensation”. The second test, called a speech formant adaptation test, examined how, over many trials, subjects learned to adapt to sustained vowel identity changes in their auditory feedback during vowel production.
Results: Results indicated that 16p11.2 deletion carriers showed an exaggerated pitch compensation response to unpredictable mid-vocalization pitch perturbations compared to sibling controls, t(7.45)=2.54, p=.037). In contrast, they showed reduced adaptation to sustained vowel identity changes in auditory feedback, (t(12)=3.04, p=.010).
Conclusions: The overcompensation response to unpredictable online auditory feedback alterations demonstrated in our participants with 16p11.2 deletion is similar to what has been observed in a subset of participants with idiopathic ASD. Our data also showed reduced speech sensorimotor adaptation following consecutive trials in which the vowel identity of auditory feedback was altered in a predictable way. A reduced adaptation response has been reported in typically developing younger children and to an even greater extent in toddlers, which may suggest a maturational dysfunction of one or more speech production mechanisms in participants with 16p11.2 deletion. This reduced speech adaptation in the context of the strong compensation response during the pitch perturbation task means that while deletion carriers were able to detect and make some effort at correcting perceived speech errors in real time, they failed to change their speech model in anticipation of highly predictable alterations in auditory feedback.