ACQ Vol 10 No 2 2008

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60 Speech Pathology Australia
Work– l i f e balance : preserv i ng your soul
Speech pathologists commonly use the
voice as a marker of the clinical disease
state. In the case of Parkinson’s disease,
for example, imprecise consonant and
vowel production combined with changes
in pitch variability often leads to a diagnosis
of dysarthria. Moreover, changes in these
speech characteristics tell us something
about the progression of the disease. In a
similar way, the voice has demonstrated
its potential as a marker of central nervous
system functioning in several populations not considered part
of our core business. The influence of depression, anxiety or
fatigue on an individual’s functioning is difficult to quantitatively
capture using existing psychometric assessments, as examination
relies on a combination of subjective clinician/patient report
and neuropsychological assessments. As neuropsychological
tests have provided equivocal results in central nervous sys­
tem disorders that contain intrinsic emotional changes, the
voice has been considered as an objective and non-invasive
alternative.
It is clear that the voice has strong face validity as a
qualitative marker of neurophysiological functioning. Patients
with depression can be recognised by their reduced rate of
speech and diminished pitch variation. A similar vocal pattern
manifests in populations undergoing extended periods of
sustained wakefulness. These observable clinical disturbances
in motor functioning combine with cognitive and emotional
disturbances to provide the assessor with a psychopathological
profile that reflects changes in the central nervous system.
Aside from instrumental investigations, the majority of
clinical evaluations continue to rely on subjective patient/
clinician report to determine the type and level of impairment.
Perceptual or listener-based analysis of vocal changes related
to emotion and physicality are important in the diagnosis and
evaluation of pathological conditions. However, perceptual
measurements are subjective, and have inherently poor intra-
and inter-rater reliability. Having quantitative information
about changes in the voice acoustic profile of a patient or
participant can contribute to the accuracy of current subjective
assessment protocols.
Although the rationale for using the voice as a marker of
clinical change has been established, capturing these changes
on a large scale is challenging. Historically, voice studies have
involved small sample sizes and idiosyncratic voice acquisition
hardware/software configurations that lack utility and are
labour intensive. This process has intrinsically higher costs
related to personnel and equipment requirements. Further­
more, commercially available software and hardware designed
to collect and analyse data can be cumbersome and com­
plicated, often requiring extensive user expertise, which can
further drain the financial resources of a clinical trial or study.
In this context, easy to use voice recording procedures and
automated analysis needs to be developed and validated. The
application of fully automated, fast and accurate voice
acoustic regimes has the potential to extend voice assessment
beyond speech pathology to a wider clinical and commercial
audience. For example, the voice could be used as a marker of
clinical change in pharmaceutical trials for depression, or, as
it has in the past, as an indicator disease state in a pathological
population. This stream of research offers a number of
opportunities not previously available to speech pathologists
through unique collaborations with big business and through
Outside the Square
The voice as a behavioural probe of emotional/neurophysiological disorders
Adam Vogel
Adam Vogel completed a BA (Psychology) in 2000 and
Masters of Speech Pathology Studies in 2003 at the
University of Queensland. He spent the first few years
after graduation working in London within the Neuro­
disability Service at Great Ormond Street Hospital. Since
returning to Australia, Adam has been working as a speech
pathologist and researcher in the Friedreich Ataxia Clinic
at the Monash Medical Centre and as a clinical scientist
for CogState Limited. He is currently completing a PhD
at the Centre for Neuroscience, University of Melbourne.
Correspondence to:
Adam Vogel
CogState Limited
Level 7, 21 Victoria Street,
Melbourne, Victoria, 3000
email:
the exploration of populations not typically under the care of
our profession.
Within this framework, careful analysis of the voice can be
considered a behavioural probe of emotional/neuro­
physiological disorders, with potentially greater sensitivity
than existing neuropsychological approaches.
Adam Vogel