Single Word Intelligibility of Individuals with Parkinson’s Disease in Noise: Pre-Specified Secondary Outcome Variables from a Randomized Control Trial (RCT) Comparing Two Intensive Speech Treatments (LSVT LOUD vs. LSVT ARTIC)
Schulz, G., Halpern, A., Spielman, J., Ramig, L., Panzer, I., Sharpley, A., & Freeman, K. (2021). Single Word Intelligibility of Individuals with Parkinson’s Disease in Noise: Pre-Specified Secondary Outcome Variables from a Randomized Control Trial (RCT) Comparing Two Intensive Speech Treatments (LSVT LOUD vs. LSVT ARTIC). Brain sciences, 11(7), 857. https://doi.org/10.3390/brainsci11070857
What is it about?
This article reports on a randomized controlled trial (RCT) examining the effects of intensive speech treatment on word intelligibility in the presence of background noise in 58 patients with Parkinson’s disease (PD). One group of patients with PD received treatment targeting voice (LSVT LOUD®), a second received treatment targeting articulation (LSVT ARTIC™), and a third group received no treatment (NO TX). Before and after treatment, the patients were audio-recorded reading 48 word pairs from the diagnostic rhyme test. The DRT is a closed set (two word) selection test of rhyming word pairs in which the initial consonant of each word pair differs based upon one of six distinctive perceptual features (compactness, graveness, sibilation, sustention, nasality, or voicing). Background babble noise and background mall noise were then added to the audio files.
Listeners were presented with pre-treatment (mall, babble and no-noise) and post-treatment (mall, babble and no-noise) files. As each word was played, both words in the matched pair appeared on the screen and the listener was asked to indicate which word they heard by pressing one of two buttons. Intelligibility was measured by examining the average of the feature scores for each word. Results showed that speech intelligibility of words in the presence of both noise conditions improved in PD participants who had LSVT LOUD compared to the groups that had LSVT ARTIC or no treatment.
Why is it important?
We know that people with PD have more difficulty being understood especially when speaking in the presence of background noise. Difficulty being understood likely contributes to significant declines in quality of life. The findings from our randomized control study demonstrated that LSVT LOUD treatment has a positive effect on improving word intelligibility in PD speakers in both quiet and background noise conditions. When added to the results of the Levy et al., 2020 study, we have demonstrated that LSVT LOUD treatment improves the ability of PD speakers to be understood. The ability to be understood can improve the quality of life for people with PD and this is really what the goal of any therapy should be, so it is exciting to be able to report these results.
Perspectives
For additional perspectives on this treatment study and line of treatment research, we asked lead researchers and co-authors on this study Dr. Geralyn Schulz, PhD, CCC-SLP and Dr. Lorraine A. Ramig, PhD, CCC-SLP a few questions. Their insights are provided below.
Why did you want to study speech intelligibility following a voice treatment?
We wanted to study word intelligibility in the presence of background noise because we know this is a situation that makes being understood particularly difficult for people with PD. In addition, we chose to study single words because we are interested in what speech production impairment specifically contributes to intelligibility. Sentence level measures are not constructed to control several factors that contribute to variability in intelligibility scores. For example, two PD speakers can have the same overall sentence intelligibility score but very different speech deficiencies contributing to those same intelligibility scores.
What were the key take away points from this study?
Word intelligibility for people with PD deteriorates in the presence of background noise. The increased intelligibility of words following intensive voice treatment can be attributed to the improvements in overall prosodic and articulatory systems following this treatment that have been well documented.
How might this impact SLPs who are working with people with Parkinson disease?
Our speakers with PD were the same as those in the Levy et al. (2020) study, and therefore, our results point to the fact that if speakers with PD have reductions in single word intelligibility in background noise, they will also have reductions in intelligibility at “higher” levels of speech production, such as at the sentence level and possibly at the conversational level, as suggested by prior researchers. This observation has clinical implications in that the use of single words to assess intelligibility is a much less difficult task for dysarthric participants than “higher” levels of speech production and so may be easier to collect clinically.
Were there any surprises or key things you learned?
Although both treatment groups demonstrated an increase in word intelligibility compared to the untreated PD group post-treatment, LSVT LOUD improved word intelligibility to a greater degree than LSVT ARTIC. Additionally, our results demonstrated a significant relationship between loudness and word intelligibility such that as loudness (SPL) increased, mean DRT scores also increased, especially in the two noise conditions. Thus, an increase in loudness is positively associated with an increase in word intelligibility and supports, at least in part, that an increase in the prosodic feature of vocal loudness promotes increased intelligibility more than a focus on articulation.
What happens next in terms of your research on LSVT LOUD?
We will examine the specific types of distinctive feature errors for the initial consonants from this study to assess the speech production problems that people with PD have prior to and following treatment (LSVT LOUD and LSVT ARTIC). These results will further our understanding of the benefits of each type of therapy on consonant production and will help to determine what characteristics of consonants may contribute the most to word intelligibility.
Download the full article HERE.
About the Authors
Geralyn Schulz, Ph.D., CCC-SLP
Dr. Schulz received her PhD from the University of MD in 1994. She worked at the National Institutes of Health as a research speech pathologist for 13 years, taught at the University of FL for 5 years and then returned to the DC area to chair the department of Speech, Language, & Hearing Sciences at the George Washington University (2000-2007). She was Associate Dean for Research at GW (2007-2014) where among other duties she administered several yearly internal grant competitions, and is now back in her home department where she has resumed teaching both at the undergraduate and graduate level. Her research has concentrated on the neurophysiology of the speech, voice and language problems in Parkinson’s Disease and the effect of various surgical interventions for PD voice, speech, & language. She is also serving as the Perspectives Editor for the ASHA Special Interest Group on TelePractice. Dr. Schulz is the Grant Coordinator for LSVT Global; she oversees all aspects of the LSVT Small Student Grant program for graduate students in Speech Pathology, Physical Therapy, and Occupational Therapy from preparing submission guidelines, soliciting submissions, through soliciting reviewers and the awarding of grants.
Lorraine Ramig, Ph.D., CCC-SLP
Dr. Ramig pioneered the Lee Silverman Voice Treatment (LSVT) for persons with Parkinson’s disease, and spearheaded over 25 years of research funded by the National Institutes of Health (NIH) and other organizations to support its development, efficacy studies, and implementation. As Chief Scientific Officer (CSO) at LSVT Global, Inc., she continues to direct research in LSVT LOUD and is faculty for LSVT LOUD training and certification courses. She received her doctorate from Purdue University and has been a Professor in the Department of Speech, Language, and Hearing Science at the University of Colorado-Boulder, Senior Scientist at the National Center for Voice and Speech in Denver, and Adjunct Professor at Columbia University. Dr. Ramig holds Honors and is a Fellow of the American Association of Speech-Language Pathologists and Audiologists (ASHA), in addition to many other awards and honors. She was born and raised in northern Wisconsin and currently resides in New York City.