Page 255 - DENG504_LINGUISTICS

Unit 18: Rhythm

speaker. The findings are discussed in relation to previous findings of dysprosody in RHD Notes
populations, and in relation to syllable-timed speech of people with other neurological conditions.

The writer is not advised to try consciously for special rhythmic effects. He ought,
however, to learn to recognize rhythmic defects in his own prose as symptoms of
poor or defective arrangement of sentences and sentence elements.

An area of interest for many researchers has been the production and comprehension of prosody
by individuals with right hemisphere damage (RHD). The literature often states that the right
hemisphere plays a crucial role in processing prosody and a general dysprosody has been suggested
for individuals with RHD. Most previous studies have concentrated on stress and intonation with
little attention paid to other aspects of prosody such as rhythm or intensity. The present study
aims to take a step in the direction of an analysis of rhythm in speakers with RHD by applying an
acoustic measure of speech rhythm. The paper begins with a summary of the mixed findings
concerning prosody in speakers with RHD, and then approaches to the analysis of rhythm are
discussed before the experimental work is presented.
Prosody in speakers with RHD
The impetus for the study of prosody in RHD populations comes from clinical observations that
prosody is disrupted in these individuals. The disruption is often referred to as 'dysprosody'
following Monrad-Krohn's (1947) term for a similar phenomenon in a patient with damage to the
left frontal region of the brain.
However, the findings about the right hemisphere's role in prosody are mixed and often differ
with respect to the function of prosody under study. Many researchers propose a binary division
between linguistic and affective prosodic functions. Linguistic functions of prosody include: stress
differences between otherwise identical words (`record (noun) and re`cord (verb)), the marking of
syntactic boundaries (old men (,) and women were there), and the indication of the speaker's
illocutionary act (question vs. statement). The affective, or paralinguistic functions of prosody
inform the listener about the emotions and attitudes of the speaker.
The lateralisation of different prosodic functions has also been a focus of research. Baum and Pell
summarise four different hypotheses for the lateralisation of prosody in the brain. The first
hypothesis is that all functions of prosody are lateralised to the right, whilst the second says that
only affective prosody is right lateralised whilst linguistic functions are associated with the left
hemisphere. A third hypothesis is that there is no lateralisation, as the neural basis of prosody is
subcortical, whilst the fourth states that individual prosodic cues can be independently lateralised.
The evidence for a strict lateralisation of prosody to the right hemisphere is equivocal (Baum and
Pell, 1999, p. 592). The results of existing studies are mixed and seem to depend a great deal on
whether the analysis undertaken is perceptual or acoustic, whether affective or linguistic prosody
is tested and whether production or comprehension is the focus of the study. Additionally, few
studies look at linguistic and affective prosody in the same participants. In conclusion to their
review of the evidence for the neural bases of prosody, Baum and Pell (1999, p. 602) report only
'weak support of differential lateralization of prosodic cues as an index of their linguistic or
affective communicative function in speech'.
Despite the large body of work on prosodic lateralisation, one aspect of prosody that has been
little described in the literature on RHD is the production or perception of rhythm. Rhythm is
studied less frequently than stress or intonation in both normal and clinical populations. This is
likely to be because, for reasons explained in the next section, rhythm is difficult to define and
measure. Although rhythm is little studied it in fact offers a different level of prosody for
examination. Rhythm cannot be defined as having either a linguistic or affective function. Rather

LOVELY PROFESSIONAL UNIVERSITY 249