Speech Intelligibility During Clinical and Low Frequency

John J Sidtis; Diana Van Lancker Sidtis; Ritesh Ramdhani; Michele Tagliati

doi:10.3390/brainsci10010026

Speech Intelligibility During Clinical and Low Frequency

Brain Sci. 2020 Jan 2;10(1):26. doi: 10.3390/brainsci10010026.

Authors

John J Sidtis^{1

2}, Diana Van Lancker Sidtis^{1

3}, Ritesh Ramdhani⁴, Michele Tagliati⁵

Affiliations

¹ Brain and Behavior Laboratory, Geriatrics Division, the Nathan Kline Institute, 140 Old Orangeberg Road, Building 35, Orangeburg, NY 10962, USA.
² Department of Psychiatry, New York University-Langone School of Medicine, 550 First Avenue, New York, NY 10016, USA.
³ Department of Communicative Sciences and Disorders, New York University Steinhardt School, 665 Broadway, 9th Floor, New York, NY 10012, USA.
⁴ Department of Neurology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, 500 Hofstra University, Hempstead, NY 11549, USA.
⁵ Department of Neurology, Cedars-Sinai Medical Center, 127 S San Vicente Blvd, AHSP A6318, Los Angeles, CA 90048, USA.

Abstract

: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become an effective and widely used tool in the treatment of Parkinson's disease (PD). STN-DBS has varied effects on speech. Clinical speech ratings suggest worsening following STN-DBS, but quantitative intelligibility, perceptual, and acoustic studies have produced mixed and inconsistent results. Improvements in phonation and declines in articulation have frequently been reported during different speech tasks under different stimulation conditions. Questions remain about preferred STN-DBS stimulation settings. Seven right-handed, native speakers of English with PD treated with bilateral STN-DBS were studied off medication at three stimulation conditions: stimulators off, 60 Hz (low frequency stimulation-LFS), and the typical clinical setting of 185 Hz (High frequency-HFS). Spontaneous speech was recorded in each condition and excerpts were prepared for transcription (intelligibility) and difficulty judgements. Separate excerpts were prepared for listeners to rate abnormalities in voice, articulation, fluency, and rate. Intelligibility for spontaneous speech was reduced at both HFS and LFS when compared to STN-DBS off. On the average, speech produced at HFS was more intelligible than that produced at LFS, but HFS made the intelligibility task (transcription) subjectively more difficult. Both voice quality and articulation were judged to be more abnormal with DBS on. STN-DBS reduced the intelligibility of spontaneous speech at both LFS and HFS but lowering the frequency did not improve intelligibility. Voice quality ratings with STN-DBS were correlated with the ratings made without stimulation. This was not true for articulation ratings. STN-DBS exacerbated existing voice problems and may have introduced new articulatory abnormalities. The results from individual DBS subjects showed both improved and reduced intelligibility varied as a function of DBS, with perceived changes in voice appearing to be more reflective of intelligibility than perceived changes in articulation.

Keywords: Parkinson’s disease; articulation; deep brain stimulation; speech; voice.

Abstract

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