Purpose: To examine the proposal that introversion predictably influences extralaryngeal and vocal behavior in vocally healthy individuals compared with individuals with extraversion and whether differences are of a nature that may support a risk hypothesis for primary muscle tension dysphonia.Method: Fifty-four vocally healthy female adults between the ages of 18 and 35 years were divided into 2 groups: introversion (n= 27) and extraversion (n= 27). All participants completed a psychological stress reactivity experiment. Before, during, and after the stressor (public speaking), participants were assessed on extralaryngeal muscle activity (surface electromyography: submental, infrahyoid; control site: tibialis anterior), perceived vocal effort, and vocal acoustics (fundamental frequency and intensity).Results: Participants in the introversion group exhibited significantly greater infrahyoid muscle activity throughout the protocol and during perceived stress than participants in the extraversion group. For both groups, perceived vocal effort significantly increased during stress, and acoustic measures significantly decreased. Infrahyoid muscle activity during the stress phase was significantly correlated with introversion and Voice Handicap Index scores but not with vocal effort scores.Conclusions: The data provided evidence of distinct differences in extralaryngeal behavior between introverts and extraverts. The findings are consistent with the trait theory of voice disorders (Roy & Bless, 2000).

Speech is a promising biomarker for schizophrenia spectrum disorder (SSD) and major depressive disorder (MDD). This proof of principle study investigates previously studied speech acoustics in combination with a novel application of voice pathology features as objective and reproducible classifiers for depression, schizophrenia, and healthy controls (HC). Speech and voice features for classification were calculated from recordings of picture descriptions from 240 speech samples (20 participants with SSD, 20 with MDD, and 20 HC each with 4 samples). Binary classification support vector machine (SVM) models classified the disorder groups and HC. For each feature, the permutation feature importance was calculated, and the top 25% most important features were used to compare differences between the disorder groups and HC including correlations between the important features and symptom severity scores. Multiple kernels for SVM were tested and the pairwise models with the best performing kernel (3-degree polynomial) were highly accurate for each classification: 0.947 for HC vs. SSD, 0.920 for HC vs. MDD, and 0.932 for SSD vs. MDD. The relatively most important features were measures of articulation coordination, number of pauses per minute, and speech variability. There were moderate correlations between important features and positive symptoms for SSD. The important features suggest that speech characteristics relating to psychomotor slowing, alogia, and flat affect differ between HC, SSD, and MDD.

Purpose: Therapies for certain voice disorders purport principles of skeletal muscle rehabilitation to increase muscle mass, strength, and endurance. However, applicability of limb muscle rehabilitation to the laryngeal muscles has not been tested. In this study, the authors examined the feasibility of the rat thyroarytenoid muscle to remodel as a consequence of increased activity instantiated through chronic electrical stimulation. Method: Twenty adult Sprague-Dawley rats ( Rattus norvegicus), assigned to a 1-week or 2-week stimulation group, were implanted with a nerve cuff electrode placed around the right recurrent laryngeal nerve and were fitted with a head connector. All animals were placed under anesthesia twice a day for 1 hr each time. Following the training, rats were killed, and thyroarytenoid muscles were isolated for histology and immunohistochemistry. Results: Mean muscle fiber area decreased, neuromuscular junction density increased, mitochondrial content increased qualitatively, and glycogen-positive fibers increased, demonstrating exercise-induced changes similar to those seen in limb muscles after endurance training. Conclusion: Rat thyroarytenoid muscles are capable of remodeling in response to chronic electrical stimulation.

The objectives of this study were to examine whether the personality trait of stress reaction (SR), as assessed with the Multidimensional Personality Questionnaire-Brief Form (MPQ-BF), (1) influences prefrontal and limbic area activity during overt sentence reading and if (2) SR and associated individual differences in prefrontal and limbic activations correlate with sensorimotor cortical activity during overt sentence reading. Ten vocally healthy adults (22–57 years) participated in a functional MRI study using an event-related sparse sampling design to acquire brain activation data during sentence production tasks (covert, whispered, overt). The outcome measure was the blood oxygenation level-dependent signal change in prefrontal, limbic, and primary somatosensory (S1) and motor cortices (M1). Significant positive correlations were found between SR scores and S1, dorsolateral prefrontal cortex (both r =.73, p <.05), and periaqueductal gray (r =.88, p <.01) activity. M1 activity was positively correlated with SR (r =.64, p <.05) and negatively with social potency (r = −.70, p <.05). Our findings suggest that motor cortical control subserving voice and speech production varies with expression of selected personality traits. Future studies should investigate the functional significance of personality differences in the central neural control of vocalization.