Phonetic learning abilities in ageing francophone speakers

This study is part of a larger research project aiming at investigating phonetic learning abilities in speakers affected by speech disorders, focusing here on ageing francophone speakers.
Our goals are twofold. First, we seek to characterize the ability of aged non pathological speakers to acquire new phonetic variants in the context of the debate on the flexibility, in adult life, of the cognitive mechanisms involved in speech production and perception. Second, we intend to use the paradigm so developed in order to complement the diagnosis of a variety of pathologies, affecting in particular brain-damaged patients who, in practice, are mostly aged patients. We aim at contributing to the development of valuable speech-based assessment tools applicable to (non-)pathological francophone speakers.
Eighteen French native speakers (9 male, 9 female) aged 60 to 80 participated in the experiment. Stimuli were 5 C[t]V[a] pseudo-words of respectively 20-, 40-, 60-, 80-, and 100-ms VOT (all other acoustic properties similar). The paradigm consisted first in an AX discrimination task, then in a reproduction task (instructions: 'please repeat as faithfully as possible') involving all stimuli. Another reproduction task involving only 60-ms VOT stimuli was also performed before discrimination, after discrimination and after the main reproduction task. On the following day, speakers performed a denomination task (French words 'pas', 'tas', 'k') and were submitted to a linguistic biography questionnaire, an air conduction audiometry test, and an anamnestic interview.
Overall, discrimination performances proved to be moderate, exhibiting large inter-individual variability and general improvement over time. The statistical analysis of manually measured VOT revealed that: (i) overall, response VOT fairly matched stimulus VOT in the main reproduction task; (ii) the reproductions of 60-ms VOT stimuli were significantly closer to the target after than before the main reproduction task. The significant interaction between Speaker and Task will be discussed at the conference, based on the relationships between individual (linguistic, medical) history and performances in both discrimination and production.