Research

Role of Altered Auditory Feedback and Principles of Motor Learning in Improving Speech Intelligibility in People with Parkinson's Disease

(PI: Kaipa, Ph.D.)

The overarching goal of this study to is to develop an evidence-based treatment protocol for speech rate deficit in people with Parkinson’s disease. Accelerated speech is a common speech deficit in individuals diagnosed with hypokinetic dysarthria secondary to Parkinson’s disease. The current study seeks to address this gap by administering a popular rate control approach, delayed auditory feedback within the context of motor learning guided approach. It is hypothesized that people with hypokinetic dysarthria secondary to Parkinson’s disease will not only demonstrate a slower rate speech rate and increased speech intelligibility after receiving this treatment, but also retain this behavior on a long-term basis. This hypothesis will be tested by: (1) comparing participants’ speech rate at baseline and post-treatment using appropriate acoustic measures, (2) comparing the speech intelligibility before and after administration of the rate control treatment, and (3) comparing the outcomes at 1-month post-treatment to baseline to evaluate long-term retention of the behavior.

This study is a phase I clinical trial and will employ a pre-test/post-test research design to evaluate the effectiveness of the rate control treatment in people with hypokinetic dysarthria secondary to Parkinson’s disease. The treatment will be administered for six consecutive days. The participants’ acoustic as well as speech intelligibility measures will be analyzed at baseline, immediately at the end of treatment session on day 6, as well as one-month after the termination of the treatment to assess for long-term retention.

Past Research

Profiling Predictors of Speech Intelligibility in Individuals with Parkinson’s Disease (PIs: Hernandez & Kaipa)

Parkinson's disease (PD) is characterized by speech deficits, that is collectively referred to as hypokinetic dysarthria (Duffy, 2013). The speech deficits range from speech rate problems to hypernasality. However, what remains currently unknown is the extent to which these speech deficits affect the speech intelligibility of individuals with PD. To address this shortcoming, the current study aims to identify the perceptual predictors of speech intelligibility in individuals with PD and the magnitude of each of these predictors on speech intelligibility as perceived by semi-trained listeners.

Status: Data collection for this project is completed.
Perceptual evaluation of speech intelligibility of individuals with Parkinson’s disease following speech rate modification through altered auditory feedback (PIs: Kaipa & Miller)

Parkinson’s disease (PD) is a neurodegenerative, progressive disease that presents with numerous symptoms, including motor and non-motor (Jankovic, 2008). About 89% of people diagnosed with PD present with communication problems (Liotti et al., 2003). There has been some research to document that people with PD present with a characteristic accelerating speech rate, commonly referred to as festinating speech (Duffy, 2013; Skodda, 2011; Skodda & Schlegel, 2008). A commonly recommended technique to treat speech rate deficits in individuals with PD is rate reduction (Hammen & Yorkston, 1996; Tjaden & Wilding, 2011). A majority of the studies have demonstrated beneficial effects of rate reduction (Hammen & Yorkston, 1996; Tjaden & Wilding, 2011). Various rate reduction strategies have been used in the past to modify the speech rate in individuals with PD (Blanchet & Snyder, 2010). The use of altered auditory feedback (AAF) has received considerable attention as a treatment technique to modify the rate of speech. The two common types of AAF include delayed auditory feedback (DAF) and frequency-shifted feedback (FSF). Previous studies have delayed the auditory feedback ranging from 25 milliseconds to 200 milliseconds and shifted the frequency of auditory feedback ranging from -1/2 octave to +1/2 octave (Lowit et al., 2010; Natke, Grosser, & Kalveram, 2001). While examining the acoustic bases of rate reduction is important, it has limited ecological validity. It is imperative to examine if the rate reduction as reflected by acoustic parameters translates to improved speech intelligibility to the outside world. This is possible only by perceptual evaluation of the individual’s speech intelligibility by naïve listeners. Considering these two limitations of the reviewed literature, the current study aims to evaluate the speech intelligibility in individuals with PD following rate modification using AAF.

Status: Data collection for this project is completed.
Perception of Emotions in Music and Speech in People with Parkinson's disease and Healthy Age-Matched Controls (PIs: Kaipa & McGuigg)

Parkinson’s disease (PD) is a disorder most commonly associated with visible motor deficits but may also result in compromised emotional processing abilities. The impact of PD on emotional processing has been documented in clinical trials signifying issues in identifying emotions (Benke, Bossch, & Andree, 1998) as well as decreased sensitivity ratings of the valence of emotions as presented through speech productions (Dara, Monetta, & Pell, 2007). Past research has suggested that listeners recognize vocal emotions based on speech prosody which is processed by the basal ganglia (Dara, Monetta, & Pell, 2008). People with PD also encounter issues identifying emotions presented through non-verbal modalities such as music. Recent research has reflected this hypothesis, finding that participants with PD struggle to recognize the emotions “anger” and “fear (Van Tricht, Smeding, Speelman, & Schmand).” Only one study has compared the processing abilities of verbal and non-verbal emotions (e.g., music) in people with PD and found differences in perception abilities (Lima et. Al., 2013). The current study aims to investigate how people with PD perceive emotions in speech and music in comparison to age-matched healthy controls. The results of this study will determine whether the emotional deficit is modality-specific or generalized to other modalities serve as an addition to current research contributions in the area.

Status: Data collection for this project is completed.
Pitch Perception and Production in children diagnosed with suspected Childhood Apraxia of Speech and healthy controls (PIs: Kaipa & Tolf)

Pitch Perception and Production in children diagnosed with suspected Childhood Apraxia of Speech and healthy controls (PIs: Kaipa & Tolf)
Childhood Apraxia of Speech is a motor speech disorder characterized by deficits in articulation and prosody (Morgan & Vogel, 2008). Although reported over 50 years ago, etiology is still unknown (ASHA, 2007). This disorder is often described as suspected Childhood Apraxia of Speech (sCAS) due to the controversy surrounding it including denial of disorder, disagreement on etiology and localization, and disagreement on primary and secondary characteristics (Peter & Stoel-Gammon, 2005). ASHA’s technical report on CAS identified the three most agreed upon features for diagnosis which included “(a) inconsistent errors on consonants and vowels in repeated productions of syllables or words, (b) lengthened and disrupted co-articulatory transitions between sounds and syllables, and (c) inappropriate prosody, especially in the realization of lexical or phrasal stress” (ASHA, 2007). A commonly investigated theme in sCAS is the deficit that is seen in prosody. Some of the deficits have been found in children with sCAS include deficits in lexical stress (Shriberg, Aram, & Kwiatkowski, 1997), vowel duration (Nijland, Maassen, & Van der Meulen, 2003), and timing accuracy (Peter & Stoel-Gammon, 2008). These deficits have been found in the production of prosody, but there has been little research on the perception of prosody in this population. The current study aims to investigate perception and perception of prosody in children with sCAS and typically developing controls as measured by the identification and production of increased vowel duration in CVC words. The outcome measure of the perception portion will be the percentage of accurate responses. Production outcome measures will be a comparison of the adult model and child model using a Pearson’s Product Moment Correlation, r, to compensate for the difference in the rate of speech between adults and children.

Status: Data collection for this project is completed.
The role of Massed versus Distributed Practice in Learning of Novel Foreign Utterances (PIs: Kaipa & Howard)

The role of several Principles of Motor Learning (PMLs) remains to be investigated in regard to speech motor learning. One such motor learning principle is the practice distribution. Distribution of practice refers to how a given practice regime is spaced across time and it ranges from massed to distributed practice (Rohrer & Taylor, 2006). In massed practice, individual practices a certain number of trials in a fixed amount of time without rest or with very short intervals between practice trials or sessions. On the other hand, in distributed practice, the individual practices the same number of trials across multiple sessions with sufficient intervals between each practice session (Magill, 2004). The role of practice distribution in non-speech motor learning has been well established. However, it remains to be known if spacing out practice sessions (distributed) is beneficial over cramming (massed) practice sessions in speech-motor learning. The current study compares the role of massed versus distributed practice in learning novel foreign language utterances.

Status: The outcomes of this project have been published and are available on the Human Kinetics Journal.