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Speaking with Intent: Acoustic Changes Following Intentional Speech Training in Parkinson’s Disease

Kodai Noguchi, M.S., Hayley S. Arnold, Ph.D., CCC-SLP, Jennifer M. Roche, Ph.D., Lynn V. Berk, M.A., CCC-SLP, Megan L. Malone, M.A., CCC-SLP, Jennifer Visker, M.A., CCC-SLP, Mya West, & Erin Kolonich, M.A., CCC-SLP

Kent State University, Speech Pathology & Audiology, Kent, OH

Research Objectives

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Background

Method

Discussion

Results

References

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Conclusion

Parkinson’s Disease (PD) disrupts the basal ganglia circuitry governing automatic speech, leading to reduced intensity, limited fundamental frequency (F0) variation, and unstable phonation.

Dual-process models distinguish between automatic and effortful processing.4, 9 Athough the automatic pathway is disrupted in PD, the pyramidal tract pathways remain preserved.

SPEAK OUT!® is a therapy designed to prompt a shift from automatic to intentional, deliberate speech.

Prior research typically utilized 480 minutes across 12 sessions1,2,3,5,7 & 8, leaving a gap in knowledge regarding whether a reduced dosage could still yield meaningful acoustic gains.

There is also a lack of research examining four key acoustic dimensions (i.e., vocal intensity, intensity variability, fundamental frequency modulation, and phonation stability) within a unified connected speech analysis.1,2,3,5,7 & 8

  1. To evaluate the effectiveness of a reduced treatment dosage (240 minutes across 8 sessions) of SPEAK OUT!®
  2. To examine improvements across four acoustic dimensions in connected speech
  3. To compare acoustic outcomes across three conditions: pre-treatment baseline, initial intentional instruction, and post-treatment production

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  • Participants: Eleven individuals with PD (mean age = 66.5 years; 2 women, 9 men)
  • Intervention: Eight, 30-minute sessions delivered twice weekly over approximately four weeks (50% of the standard 12-session dosage)
  • Procedure: Participants recorded 8 SPEAK OUT!® stimulability phrases across three conditions: 1) pre, 2) pre-intent (stimulability), and 3) post
  • Acoustic Analysis: Features extracted via openSMILE (GeMAPS)6, focusing on four parameters: 1) Vocal effort: mean intensity, 2) Intensity modulation: intensity range, 3) Prosodic modulation: fundamental frequency (F0) range, 4) Phonation stability: jitter
  • Statistical Model: Mixed-Effects Model
  • Harmonics to Noise Ratio (HNR): Trending toward improved values, but not statistically significant (p > .05).
  • Jitter: Significantly lower (improved) post-treatment compared to the initial intentional speech instruction (β = −.41, SE = .16, t = −2.53, p = .04).
  • Intensity Range (Intensity Modulation): Increased significantly when speakers first applied intentional effort (β = −.41, SE = .15, t = −2.66, p = .02) and remained elevated post-treatment (β = .41, SE = .15, t = 2.78, p = .02).
  • Mean Intensity (Vocal Effort): Increased significantly following training relative to the pre-treatment baseline (β = .35, SE = .14, t = 2.37, p = .05).
  • Fundamental Frequency (F0) Range (Prosodic Modulation): Increased immediately after initial instruction to use intentional speech (β = .43, SE = .15, t = 2.78, p = .02).
  • Findings support the theory that deliberate speech training recruits preserved neural pathways to compensate for motor system disruptions.
  • The immediate gains in intensity and F0 range suggest that intentional effort produces rapid compensatory adjustments.
  • Phonation stability (jitter) improvements specifically emerged between the pre- and post-treatment, suggesting that structured training is required to refine neural control of voicing over time.
  • The use of acoustic measures (e.g., intensity, F0, jitter) provides objective sensitivity to speech changes that may not be captured through perceptual evaluation alone.
  • Significant gains at half the standard dosage (240 minutes + 8 sessions vs. 480 minutes + 12 sessions) suggest the intervention is more clinically accessible than previously assumed.
  • SPEAK OUT!® produces meaningful improvements across multiple acoustic dimensions even at a reduced dosage.
  • The study validates the use of intentional speech to bypass disrupted automatic motor systems underlying hypokinetic dysarthria.
  • The use of connected speech tasks and unified multi-dimensional analysis provides both theoretical and clinical insights into the minimum effective conditions for treatment.
  1. Behrman, A., Cody, J., Elandary, S., Flom, P., & Chitnis, S. (2020). The effect of SPEAK OUT! and The LOUD Crowd on dysarthria due to Parkinson’s disease. American Journal of Speech-Language Pathology, 29(3), 1448–1465. https://doi.org/10.1044/2020_AJSLP-19-00024
  2. Behrman, A., Wilson, M., Cody, J., Elandary, S., & Chitnis, S. (2019, June). The effect of intentional speech on prosody in Parkinson disease [Poster presentation]. Lead with INTENT Symposium, Richardson, TX, United States. https://parkinsonvoiceproject.org/program/research/
  3. Boutsen, F., Park, E., Dvorak, J., & Cid, C. (2018). Prosodic improvement in persons with Parkinson disease receiving SPEAK OUT!® voice therapy. Folia Phoniatrica et Logopaedica, 70(2), 51–58. https://doi.org/10.1159/000488875
  4. Chaiken, S., & Ledgerwood, A. (2012). A theory of heuristic and systematic information processing. In P. A. M. Van Lange, A. W. Kruglanski, & E. T. Higgins (Eds.), Handbook of theories of social psychology (pp. 246–266). Sage Publications Ltd. https://doi.org/10.4135/9781446249215.n13
  5. Cleveland, S., Pimentel, J., Talarico, M., & Solomon, J. (2015, June). Vocal intensity and speech intelligibility pre- and post-SPEAK OUT!® treatment [Poster presentation]. Lead with INTENT Symposium, Richardson, TX, United States. https://parkinsonvoiceproject.org/program/research/
  6. Eyben, F., Scherer, K. R., Schuller, B. W., Sundberg, J., André, E., Busso, C., ... & Truong, K. P. (2015). The Geneva minimalistic acoustic parameter set (GeMAPS) for voice research and affective computing. IEEE Transactions on Affective Computing, 7(2), 190–202. https://doi.org/10.1109/TAFFC.2015.2457417
  7. Levitt, J. S., & Walker-Batson, D. (2018). The effects of the “speak with intent” instruction for individuals with Parkinson’s disease. Journal of Communication Disorders Assistive Technology, 1, 1–15.
  8. Parveen, S. (2020). Group-based intervention of participants with Parkinson disease: Findings from a 6-month LOUD Crowd® program. Clinical Archives of Communication Disorders, 5(2), 96–105. https://doi.org/10.21849/cacd.2020.00241
  9. Tversky, A., & Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. Science, 185(4157), 1124–1131. http://www.jstor.org/stable/1738360