ObjectiveThis study examined adaptive responses to auditory perturbation of fundamental frequency (f o ) in speakers with Parkinson's disease (PD) and control speakers. MethodSixteen speakers with PD and nineteen control speakers produced sustained vowels while they received perturbed auditory feedback (i.e., f o shifted upward or downward). Speakers' pitch acuity was quantified using a just-noticeable-difference (JND) paradigm. Twelve listeners provided estimates of the speech intelligibility for speakers with PD. ResultsFifteen responses from each speaker group for each shift direction were included in analyses. While control speakers generally showed consistent adaptive responses opposing the perturbation, speakers with PD showed no compensation on average, with individual PD speakers showing highly variable responses. In the PD group, the degree of compensation was not significantly correlated with age, disease progression, pitch acuity, or intelligibility. ConclusionsThese findings indicate reduced adaptation to sustained f o perturbation and higher variability in PD compared to control participants. No significant differences were seen in pitch acuity between groups, suggesting that the f o adaptation deficit in PD is not the result of purely perceptual mechanisms. SignificanceThese results suggest there is an impairment in vocal motor control in PD. Building on these results, contributions can be made to developing targeted voice treatments for PD.PLOS ONE | https://doi.org/10.1371/journal.pone

Purpose: The vocal auditory-motor control of individuals with hyperfunctional voice disorders was examined using a sensorimotor adaptation paradigm. Method: Nine individuals with hyperfunctional voice disorders and 9 individuals with typical voices produced sustained vowels over 160 trials in 2 separate conditions: (a) while experiencing gradual upward perturbations in the fundamental frequency (f o ) of their auditory feedback (shift-up) and (b) under no auditory perturbation (control). The shift-up condition consisted of 4 ordered (fixed) phases: baseline (no perturbation), ramp (gradual increases in heard f o ), hold (a consistently higher heard f o ), and after-effect (no perturbation). Adaptive responses were defined as the difference in produced f o during control and shift-up conditions.Results: Adaptive responses were significantly different between groups. Individuals with typical voices generally showed compensatory adaptive responses, with decreased f o during the ramp and hold phases. Conversely, many individuals with hyperfunctional voice disorders instead displayed the opposite effect by following the direction of the perturbation. When f o was experimentally increased, speakers further increased their f o . Conclusion: Results indicate that some individuals diagnosed with hyperfunctional voice disorders have disrupted auditory-motor control, suggesting atypical neurological function. These findings may eventually allow for the development of new interventions for hyperfunctional voice disorders.

Purpose While orthographic transcription (OT) is the gold standard for measures of intelligibility, it is relatively inaccessible to clinicians. This study investigates the relationship between visual analog scale (VAS) ratings and OT measures of intelligibility for speakers with Parkinson's disease (PD), with the eventual goal of developing more clinically feasible assessments of intelligibility. Method Twenty speakers with PD and 5 controls read 11 sentences. First, 33 listeners completed an OT task using 1 sentence from each speaker. An additional 33 listeners rated the intelligibility of 1 sentence from each speaker using a VAS, reflecting a minimized exposure VAS (MEV) task. Lastly, 14 additional listeners each rated the intelligibility of all 11 sentences produced by all speakers using a VAS, reflecting an extended exposure VAS (EEV) task. Smaller listener groups were simulated from each VAS task for comparison to scores from the OT task. Results There was a strong relationship between OT and both MEV and EEV. This relationship remained strong ( R 2 ≥ .82) even when only 1 listener in MEV and 2 listeners in EEV were simulated per sentence. Conclusions VAS ratings may be a suitable alternative to OT measures of sentence intelligibility for PD using listeners with both minimal and extended exposure to the stimuli.

Objectives/Hypothesis The purpose of this study was to determine the relationship among cognitive load condition and measures of autonomic arousal and voice production in healthy adults. Study Design Prospective. Methods Sixteen healthy young adults (eight females) produced a sentence containing an embedded Stroop task in each of two cognitive load conditions: congruent and incongruent. In both conditions, participants said the font color of the color words instead of the word text. In the incongruent condition, font color differed from the word text, creating an increase in cognitive load relative to the congruent condition in which font color and word text matched. Three physiologic measures of autonomic arousal (pulse volume amplitude, pulse period, and skin conductance response amplitude) and four acoustic measures of voice (sound pressure level, fundamental frequency, cepstral peak prominence, and low-to-high spectral energy ratio) were analyzed for eight sentence productions in each cognitive load condition per participant. Results A logistic regression model was constructed to predict the cognitive load condition (congruent or incongruent) using subject as a categorical predictor and the three autonomic measures and four acoustic measures as continuous predictors. It revealed that three variables were significantly associated with cognitive load condition: skin conductance response amplitude, cepstral peak prominence, and the low-to-high spectral energy ratio. Conclusions During speech produced under increased cognitive load, healthy young adults show changes in physiologic markers of heightened autonomic arousal and acoustic measures of voice quality. Future work is necessary to examine these measures in older adults and individuals with voice disorders.

Bone conduction (BC) is heavily relied upon in the diagnosis and treatment of hearing loss, but is poorly understood. For example, the relative importance and frequency dependence of various identified BC sound transmission mechanisms that contribute to activate the cochlear partition remain unknown. Recently, we have developed techniques in fresh human cadaveric specimens to directly measure scalae pressures with micro-fiberoptic sensors, enabling us to monitor the input pressure drive across the cochlear partition that triggers the cochlear traveling wave during air conduction (AC) and round-window stimulation. However, BC stimulation poses challenges that can result in inaccurate intracochlear pressure measurements. Therefore, we have developed a new technique described here that allows for precise measurements during BC. Using this new technique, we found that BC stimulation resulted in pressure in scala vestibuli that was significantly higher in magnitude than in scala tympani for most frequencies, such that the differential pressure across the partition-the input pressure drive-was similar to scala vestibuli pressure. BC (stimulated by a Bone Anchored Hearing Aid [Baha]) showed that the mechanisms of sound transmission in BC differ from AC, and also showed the limitations of the Baha bandwidth. Certain kinematic measurements were generally proportional to the cochlear pressure input drive: for AC, velocity of the stapes, and for BC, low-frequency acceleration and high-frequency velocity of the cochlear promontory. Therefore, our data show that to estimate cochlear input drive in normal ears during AC, stapes velocity is a good measure. During BC, cochlear input drive can be estimated for low frequencies by promontory acceleration (though variable across ears), and for high frequencies by promontory velocity.