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

LSVT-X successfully increased vocal SPL (which was consistent with improvements following traditional LSVT), decreased perceived voice handicap, and improved functional speech in individuals with PD. Further large-scale research is required to truly establish LSVT-X efficacy.

This study supports the use of the Companion as an aid in treatment of hypokinetic dysarthria in individuals with PD. Advantages and disadvantages of the Companion, as well as limitations of the present study and directions for future studies, are discussed.