An acoustic-perceptual investigation of the Rhythm Rule (RR), a phonologica
l phenomenon in which adjacent stresses are adjusted to avoid 'stress clash
' (e.g. thirTEEN vs THIRteen MEN), was undertaken to identify the locus of
functional impairments in speech prosody in different aphasic syndromes. Su
bjects included two left brain-damaged aphasic patients (one fluent, one no
nfluent), one right brain-damaged non-aphasic patient, and one non-neurolog
ical control. They were instructed to read sentences containing experimenta
l target words ('double stressed'; e.g, fourteen) and matching control word
s ('initial stressed': e.g, forty) in the presence of a clause boundary or
its absence. Perceptual tests indicated that rhythmic disturbances associat
ed with the RR emerged for the non-fluent aphasic only. Acoustic analysis r
evealed that duration of the final syllable was the principal, auditory cor
relate of the RR for all talkers but the non-fluent aphasic. Findings are d
iscussed in relation to issues concerning the nature and extent of disrupti
on of the RR, phonology and phonetics of the RR, and more generally dyspros
ody after brain damage.