Improving speech in individuals with Parkinson’s disease


Learn more about the scientific bases of LSVT LOUD! The evidence provided by this 1995 study formed the foundation for the next 20 years of our research in speech treatment for Parkinson disease.

Comparison of Two Forms of Intensive Speech Treatment for Parkinson Disease. Authors: Lorraine Olson Ramig, Stefanie Countryman, Laetitia L. Thompson, Yoshiyuki Horii.  Journal of Speech Language and Hearing Research, December 1995, American Speech-Language-Hearing Association (ASHA) DOI: 10.1044/jshr.3806.1232

Photo by Jaddy Liu on

What is it about?

Nearly 90% of individuals with Parkinson disease (PD) will develop speech disorders that often diminish quality of life. One of the earliest and most common problems is reduced vocal loudness which makes individuals difficult to hear and understand. This was the first speech research to compare two forms of intensive speech treatment specifically designed to improve reduced vocal loudness in PD: 1) one treatment focused on improving respiratory support for speech and 2) the other focused on improving voice. Forty-five individuals with PD participated in 16 sessions of treatment in one month. Greater improvements were measured for individuals who participated in the treatment focusing on voice.

Why is it important?

This study provided the first evidence that intensive speech treatment focusing on voice could make significant improvements in speech in PD. Furthermore, this study was the first to implement a randomized control trial (RCT) design (the gold standard of evidence) to address a critical and challenging problem for the PD community. In addition to the measures of speech and voice, patient and family reports were positive as demonstrated in the video provided below (See Related Content: Pre and post speech therapy video).


The evidence provided by this study formed the foundation for the next 20 years of our research in speech treatment for Parkinson disease. Based on the outcomes of this study, we went on to follow and report on this group of patients at one year (See Resources: LSVT one year) and two years (See Resources: LSVT two years) after treatment. Two years after one month of treatment, individuals with PD who received treatment focusing on voice in this initial study maintained their significant treatment outcomes. This is the first long-term evidence for efficacious speech treatment for PD. Through these studies, we learned many lessons about speech in PD and the underlying bases for the speech disorder in PD. Those lessons have helped us evolve the voice treatment (which is now known as LSVT LOUD) which is being delivered by 16,000 clinicians in over 60 countries and is supported by two additional RCTs (See Related Content: 2001 & 2018).

LSVT One Year purpose of this study was to evaluate the long-term (12 months) effects of two forms of speech treatment on the speech and voice deficits that occur in Parkinson’s disease. Thirty-five patients with idiopathic Parkinson’s disease were assigned to one of two speech treatment groups: voice and respiration (The Lee Silverman Voice Treatment [LSVT]) or placebo (respiration) treatment. Vocal intensity data from before, immediately after, and at 6 and 12 months after speech treatment revealed statistically significant differences between the treatment groups. Only subjects in the LSVT group improved or maintained vocal intensity above pretreatment levels by 12 months after treatment. The placebo group had statistically significant deterioration of vocal intensity levels from before to 12 months after treatment during conversational monologue. The LSVT group did not deteriorate to levels below pretreatment in vocal intensity over the 12-month period. This study is the first to document the short- and long-term effects of intensive speech treatment (LSVT), which focuses on the voice, for patients with Parkinson’s disease compared with a placebo speech treatment group.

Read Full Publication Here

LSVT Year Two

OBJECTIVES: To assess long term (24 months) effects of the Lee Silverman voice treatment (LSVT®), a method designed to improve vocal function in patients with Parkinson’s disease.

METHODS: Thirty three patients with idiopathic Parkinson’s disease were stratified and randomly assigned to two treatment groups. One group received the LSVT®, which emphasises high phonatory-respiratory effort. The other group received respiratory therapy (RET), which emphasises high respiratory effort alone. Patients in both treatment groups sustained vowel phonation, read a passage, and produced a monologue under identical conditions before, immediately after, and 24 months after speech treatment. Change in vocal function was measured by means of acoustic analyses of voice loudness (measured as sound pressure level, or SPL) and inflection in voice fundamental frequency (measured in terms of semitone standard deviation, or STSD).

RESULTS: The LSVT® was significantly more effective than the RET in improving (increasing) SPL and STSD immediately post-treatment and maintaining those improvements at 2 year follow up.

CONCLUSIONS: The findings provide evidence for the efficacy of the LSVT® as well as the long term maintenance of these effects in the treatment of voice and speech disorders in patients with idiopathic Parkinson’s disease.

Read Full Publication Here

RCT 2001

This study assessed the impact of the Lee Silverman Voice Treatment (LSVT®) on vocal loudness [sound pressure level (SPL)] in a group of dysarthric individuals with idiopathic Parkinson’s disease (IPD). Pre‐ to post‐treatment changes in SPL in the treated group were compared with changes in voice SPL during the same time in two control groups: individuals with IPD not treated with the LSVT® and in non‐disordered individuals, age‐matched to the patients. All subjects produced the same voice and speech tasks—sustaining vowel phonation, reading the “Rainbow Passage,” producing a short monologue, and describing a picture. These tasks were recorded at three different occasions: just prior to treatment, just after treatment, and 6 months following treatment. The individuals treated with LSVT® increased voice SPL from baseline to post‐treatment by an average of 8 dB and from baseline to 6 months follow‐up by an average of 6 dB. These changes were statistically significant and perceptibly audible. No significant changes in SPL were observed in the control groups during the time corresponding to the treatment and follow‐up. Differences in SPL between the treated and untreated patients at post‐treatment and follow‐up were statistically significant for all voice and speech tasks. These findings, along with others, provide additional support for the efficacy of the LSVT®. Mov. Disord. 16:79–83, 2001. © 2001 Movement Disorder Society.

Read Full Publication Here

RTC 2018

Background: As many as 89% of people with Parkinson’s disease (PD) develop speech disorders.

Objectives: This randomized controlled trial evaluated two speech treatments for PD matched in intensive dosage and high‐effort mode of delivery, differing in subsystem target: voice (respiratory‐laryngeal) versus articulation (orofacial‐articulatory).

Methods: PD participants were randomized to 1‐month LSVT LOUD (voice), LSVT ARTIC (articulation), or UNTXPD (untreated) groups. Speech clinicians specializing in PD delivered treatment. Primary outcome was sound pressure level (SPL) in reading and spontaneous speech, and secondary outcome was participant‐reported Modified Communication Effectiveness Index (CETI‐M), evaluated at baseline, 1, and 7 months. Healthy controls were matched by age and sex.

Results:  At baseline, the combined PD group (n = 64) was significantly worse than healthy controls (n = 20) for SPL (P < 0.05) and CETI‐M (P = 0.0001). At 1 and 7 months, SPL between‐group comparisons showed greater improvements for LSVT LOUD (n = 22) than LSVT ARTIC (n = 20; P < 0.05) and UNTXPD (n = 22; P < 0.05). Sound pressure level differences between LSVT ARTIC and UNTXPD at 1 and 7 months were not significant (P > 0.05). For CETI‐M, between‐group comparisons showed greater improvements for LSVT LOUD and LSVT ARTIC than UNTXPD at 1 month (P = 0.02; P = 0.02). At 7 months, CETI‐M between‐group differences were not significant (P = 0.08). Within‐group CETI‐M improvements for LSVT LOUD were maintained through 7 months (P = 0.0011).

Conclusions: LSVT LOUD showed greater improvements than both LSVT ARTIC and UNTXPD for SPL at 1 and 7 months. For CETI‐M, both LSVT LOUD and LSVT ARTIC improved at 1 month relative to UNTXPD. Only LSVT LOUD maintained CETI‐M improvements at 7 months. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society

Read Full Publication Here

Pre and Post Speech Therapy Video