The role of prosody in a case of foreign accent syndrome (FAS).

Foreign accent syndrome (FAS) is a rare disorder characterized by the emergence of a perceived foreign accent following brain damage. The symptomotology, functional bases, and neural substrates of this disorder are still being elucidated. In this case study, acoustic analyses were performed on the speech of a 46-year old monolingual female who presented with FAS of unknown aetiology. The patient had a pseudo-accent frequently described as 'Swedish' or 'Eastern European'. Stop consonant VOT, consonant burst spectra and duration, vowel durations, formant frequencies, and trajectories were analysed, along with prosodic cues for lexical stress assignment and sentence-level intonation. Results indicated VOT values were generally preserved, while there was a strong tendency to realize the English alveolar flap as a full stop, and to produce flaps that had greater-than-normal closure durations. The spectral properties of the patient's vowels resembled those of normal talkers (with the possible exceptions of decreased F1 values for /i/ and slight differences in formant dynamics for /u/, /o/, /i/, and /epsilon/). However, vowel durations were relatively long, contributing to exaggerated tense/lax contrasts. Token-to-token variability in vowel production was slightly higher than normal for duration, but not for formant frequency values. Lexical stress assignment was inaccurate and highly variable (with similar problems noted for non-speech materials), and sentence level intonation showed occasional deviations from typical American English patterns. For this patient, an underlying timing/rhythm difficulty appeared responsible for the range of segmental and suprasegmental changes leading to the impression of a foreign accent.