When auditory feedback is perturbed in a consistent way, speakers learn to adjust their speech to compensate, a process known as sensorimotor adaptation. Typically, feedback perturbation experiments employ a transformation that targets a single vowel, or that affects all vowels in the same way, resulting in a uniform change across the vowel space.
When we speak, we are able to use what we hear about that speech (auditory feedback) to alter our speech movements both in real time within a single word (feedback control) as well as over longer time scales across multiple utterances (feedforward control).
“We found that the folks with cerebellar damage responded to these unpredictable changes to a larger extent than those without any damage,” says Parrell. “It was totally unexpected.”