Participants will receive a pill/capsule with an inactive ingredient during the placebo arm of this study.

Participants will receive a pill/capsule with octanoic acid (amount determined by the participant's weight) during the experimental arm of this study.

Voice recordings were used to measure the degree of tremor in the voice. Mean post-test values for each acoustic measure were compared after the octanoic acid and placebo conditions, with and without consideration of baseline values. Mean values represent the average of two testing days. Degree of amplitude tremor shows the extent of amplitude variation as a percent of the mean signal amplitude, with lower numbers indicating less amplitude tremor. Baseline values for magnitude of amplitude tremor across all participants and conditions ranged from 4.06 to 27.09, and post-test values ranged from 1.94 to 26.02. Degree of frequency tremor shows the extent of fundamental frequency variation as a percent of the mean signal frequency, with lower numbers indicating less frequency tremor. Baseline values for magnitude of frequency tremor across all participants and conditions ranged from 1.21 to 15.31, and post-test values ranged from 0.60 to 13.86.

Three experienced listeners independently rated each participant's voice from paired sample recordings comparing the baseline to post-test samples in randomized order for each condition. Sustained vowel and sentence-level recordings were rated, with decoded samples later analyzed for 1=better for post-test compared to baseline, 0= no difference between post-test and baseline. Maximum score for each participant was 3 (post-test was better for each of three raters). The range of possible scores was the sum of each of three raters' scores (0 to 3), with 0 indicating no difference between baseline and post-test voice tremor severity rating, and 3 indicating better voice (less tremor severity) at post-testing compared to pre-testing. Mean post-test values for task were compared for the octanoic acid and placebo conditions, and all raters were blind to which sample was a baseline versus a post-test recording, and which samples were associated with the [placebo or octanoic acid conditions.](streamdown:incomplete-link)

Participants who were randomized to receive a capsule with an inactive ingredient (placebo) during the first 3 weeks of the study (placebo arm of crossover design study), and then received octanoic acid in the last 3 weeks of the study.

Placebo

Voice recordings were used to measure the degree of tremor in the voice. Mean post-test values for each acoustic measure were compared after the octanoic acid and placebo conditions, with and without consideration of baseline values. Mean values represent the average of two testing days. Degree of amplitude tremor shows the extent of amplitude variation as a percent of the mean signal amplitude, with lower numbers indicating less amplitude tremor. Baseline values for magnitude of amplitude tremor across all participants and conditions ranged from 4.06 to 27.09, and post-test values ranged from 1.94 to 26.02. Degree of frequency tremor shows the extent of fundamental frequency variation as a percent of the mean signal frequency, with lower numbers indicating less frequency tremor. Baseline values for magnitude of frequency tremor across all participants and conditions ranged from 1.21 to 15.31, and post-test values ranged from 0.60 to 13.86.

Study phase 1 or 2, when participants were randomized to the 3-week intervention phase in which an inactive capsule (placebo or inactive drug) was taken once a day for 3 weeks.