Speech Science – Vowel Acoustics in People with Parkinson’s Parkinson’s disease is a neurodegenerative disease that contributes to the progressive decline of motor function because of loss of dopamine-creating brain cells. Given the progressive decline of motor function, this disease shows characteristics of hypokinetic dysarthria as well as major signs of rigidity, tremor, and bradykinesia. In light with these effects, vowel acoustics in people with Parkinson’s disease has attracted considerable attention in recent years. Actually, for many individuals with Parkinson’s disease, hypokinetic dysarthria is a common condition, which is an indicator of motor speech disorders. Numerous studies have been carried out to examine motor speech disorders in Parkinson’s disease, particularly in relation to hypokinetic dysarthria. This paper examines some studies that have been conducted to evaluate the issue of hypokinetic dysarthria in people with Parkinson’s disease with regards to vowel acoustics. The article provides a summary of the articles and critique of the methodological issues in the studies. Summary of Articles Skodda, Gronheit & Schlegel (2012) conducted a study in which they examined whether vowel articulation in people with Parkinson’s disease is an indicator of certain changes in the progression of the disease. The study was carried out on the premise that hypokinetic dysarthria in Parkinson’s disease is a multifaceted impairment that affects different aspects of an individual’s speech including articulation, respiration, prosody and phonation. These researchers utilized a quantitative research approach i.e. pre-test, post-test study through which research participants were divided into two groups i.e. experimental group and control group. Pre-test and post-test data was collected and analyzed from each of these two groups to help answer the research question. The researchers concluded that vowel articulation in patients suffering from Parkinson’s disease is an indicator of specific changes in the progression of the disease. Vowel articulation impairment was found to be independent from global motor function though linked to gait dysfunction, vowel articulation measurement may have a potential of acting as an indicator of progression of axial disease. Watson & Munson (2008) examine Parkinson’s disease and the impact of lexical components on vowel articulation. In this regard, lexical components are phonological neighborhood density and word frequency, which are considered significant in the perception and production of speech. The study employed a pre-test, post-test quantitative...

experimental groups and control groups. The experimental group comprised 10 men who are suffering from idiopathic Parkinson’s disease whereas the control group comprised 10 healthy individuals. Audio recording of individuals in the experimental group was carried out and data was measured using Mini-Mental-Scale-Examination. The study found that Parkinson’s disease significantly affects speech and generates a more complex interaction vowel production beyond what is established in existing literature. In concurrence with previous studies, individuals with Parkinson’s disease has vowel-space dispersion. While all participants in the experimental group suffered from hypokinetic dysarthria, speech impairment severity could not be established. Bang et al. (2013) conducted a research that examined acoustic attributes of vowel sounds in individuals suffering from Parkinson’s disease. The research was geared toward describing the acoustic speech and speech attributes of Parkinson’s disease patients. This research was conducted on the premise that hypokinetic dysarthria occurs in a significant portion of patients suffering from Parkinson’s disease. Similar to the other studies, Bang et al. (2013) employed a pre-test, post-test research methodology in which data was collected from the participants prior to and after being subjected to an experimental procedure. The experimental group included seven female Parkinson’s disease patients while the control group included seven normal healthy females. The experimental procedure involved requiring each participant in the two groups to vocalize extended /a/, /e/, /i/, and /u/ vowels three times for at least 5 seconds at a comfortable voice tones and loudness (Bang et al., 2013). Data collected from these participants was analyzed using statistical analysis and predictive analysis processes. The study found that Parkinson’s disease patients exhibit impairments in tongue movement and laryngeal function. Some of these laryngeal function variables include abnormal jitter, asymmetric centralization, and decreased vowel space area. Each of the three studies employed similar methodologies in exploring the issue of vowel acoustics in people with Parkinson’s disease. The use of a pre-test, post-test research design helped to effectively examining the vowel acoustics between people with Parkinson’s disease and healthy individuals. However, there were significant differences in the data analysis processes utilized by the authors and their data interpretation to arrive at the conclusions. For…