https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0140525X00047695

Primate handedness reconsidered

The origins of cerebral lateralization in humans are traced to the asymmetric prenatal development of the ear and labyrinth. Aural lateralization is hypothesized to result from an asymmetry in craniofacial development, whereas vestibular dominance is traced to the position of the fetus during the final trimester. A right-ear sensitivity advantage may contribute to a left-hemispheric advantage in speech perception and language functions, whereas left-otolithic dominance may independently promote right-sided motoric dominance and a right-hemispheric superiority in most visuospatial functions. The emergence of handedness is linked to the assumption of an upright posture in the early hominids, whereas the failure to develop clear vestibular asymmetry may underlie the poor motoric lateralization found in several neurodevelopmental disorders.

A general theory concerning the prenatal origins of cerebral lateralization in humans.

This article reviews the literature on the efficacy of treatment for voice disorders primarily using studies published in peer-reviewed journals. Voice disorders are defined, their frequency of occurrence across the life span is reported, and their impact on the lives of individuals with voice disorders is documented. The goal of voice treatment is to maximize vocal effectiveness given the existing disorder and to reduce the handicapping effect of the voice problem. Voice treatment may be (a) the preferred treatment to resolve the voice disorder when medical (surgical or pharmacological) treatments are not indicated; (b) the initial treatment in cases where medical treatment appears indicated; it may obviate the need for medical treatment; (c) completed before and after surgical treatment to maximize long-term post-surgical voice; and (d) a preventative treatment to preserve vocal health. Experimental and clinical data are reviewed that support these roles applied to various disorder types: (a) vocal misuse, hyperfunction and muscular imbalance (frequently resulting in edema, vocal nodules, polyps or contact ulcers); (b) medical or physical conditions (e.g., laryngeal nerve trauma, Parkinson disease); and (c) psychogenic disorders (e.g., conversion reactions, personality disorders). Directions for future research are suggested which maximize clinical outcomes and scientific rigor to enhance knowledge on the efficacy of voice treatment.

Treatment efficacy: voice disorders

This study investigated the effect of two forms of intensive speech treatment, (a) respiration (R) and (b) voice and respiration (Lee Silverman Voice Treatment [LSVT]), on the speech and voice deficits associated with idiopathic Parkinson disease. Forty-five subjects with Idiopathic Parkinson disease completed extensive pretreatment neurological, otolaryngological, neuropsychological, and speech assessments. All subjects completed 16 sessions of intensive speech treatment, 4 times a week for 1 month. Pre- and post-treatment measures included intensity and maximum duration during sustained vowel phonation. Intensity, habitual fundamental frequency, fundamental frequency variability, and utterance and pause duration were measured during reading of the "Rainbow Passage" and conversational monologue as well. Family and subject self-ratings were completed pre- and post-treatment for the perceptual variables loudness, monotonicity, hoarseness, overall intelligibility, and initiation of conversation. Significant pre- to post-treatment improvements were observed for more variables and were of greater magnitude for the subjects who received the voice and respiration treatment (LSVT). Only subjects who received the LSVT rated a significant decrease post-treatment on the impact of Parkinson disease on their communication. Correlations between descriptive prognostic variables (i.e., stage of disease, speech/voice severity rating, depression, and time since diagnosis) and magnitude of treatment-related change indicated these factors did not significantly predict treatment effectiveness. These findings suggest that intensive voice and respiration (LSVT) treatment, focusing on increased vocal fold adduction and respiration, is more effective than respiration (R) treatment alone for improving vocal intensity and decreasing the impact of Parkinson disease on communication.

https://pubs.asha.org/doi/pdf/10.1044/jshr.3806.1232

Comparison of Two Forms of Intensive Speech Treatment for Parkinson Disease

This study assessed the impact of the Lee Silverman Voice Treatment (LSVT) on vocal loudness [sound pressure level (SPL)] in a group of dysarthric individuals with idiopathic Parkinson's disease (IPD). Pre- to post-treatment changes in SPL in the treated group were compared with changes in voice SPL during the same time in two control groups: individuals with IPD not treated with the LSVT and in non-disordered individuals, age-matched to the patients. All subjects produced the same voice and speech tasks--sustaining vowel phonation, reading the "Rainbow Passage," producing a short monologue, and describing a picture. These tasks were recorded at three different occasions: just prior to treatment, just after treatment, and 6 months following treatment. The individuals treated with LSVT increased voice SPL from baseline to post-treatment by an average of 8 dB and from baseline to 6 months follow-up by an average of 6 dB. These changes were statistically significant and perceptibly audible. No significant changes in SPL were observed in the control groups during the time corresponding to the treatment and follow-up. Differences in SPL between the treated and untreated patients at post-treatment and follow-up were statistically significant for all voice and speech tasks. These findings, along with others, provide additional support for the efficacy of the LSVT.

Changes in vocal loudness following intensive voice treatment (LSVT®) in individuals with Parkinson's disease: A comparison with untreated patients and normal age‐matched controls

An international standard text in the field, this edition has undergone a major rewriting by the two authors. New material has been added to cover the latest developments in the field, including the perceptual and instrumental assessment of dysphonia.

Margaret Cicely Langton Greene

Papers

The voice and its disorders