Sensorimotor Adaptation to a Nonuniform Formant Perturbation Is Preserved in Healthy Aging

Young adult speakers can be induced to increase the acoustic contrast between vowels through exposure to a nonuniform auditory "centralization" feedback perturbation that makes vowels sound less distinct from one another. While this result suggests that sensorimotor adaptation is a promising learning mechanism to drive behaviorally relevant changes related to speech intelligibility, existing res sensorimotor adaptation in speech has largely focused on younger adults. Given established age-related deficits in speech motor performance, it is possible that healthy aging itself negatively impacts speech motor learning; however, these potential effects of age are currently unknown. Here, we examine the effects of healthy aging on the magnitude of both adaptation to the complex "centralization" paradigm as well as the generalization of this learning to untrained vowels.

Forty-three neurobiologically healthy speakers (age range: 18-73 years) read monosyllabic words with corner vowels, while their auditory feedback was shifted toward the center of the vowel space. Adaptation was measured as the increase in vowel contrast induced by this perturbation. Generalization was tested in monosyllabic words with noncorner vowels produced under masking noise.

Speakers adapted to the perturbation, producing the trained corner vowels farther from the vowel center, with increased acoustic contrast among them. This learning generalized robustly to untrained noncorner vowels. Crucially, age did not affect the magnitude of adaptation nor the magnitude of the generalization.

These findings demonstrate that healthy aging does not impair sensorimotor adaptation in speech, further establishing that sensorimotor adaptation can be leveraged to drive behaviorally relevant changes in speech in older adults with acquired motor speech disorders.