Phonation is the result of aerodynamic forces acting on the vocal fold tissue subsequent to their positioning within the direct path of an expired air stream. The aerodynamic forces cause the vocal folds to oscillate and modulate the air stream. This modulation creates acoustic energy we refer to as “voice”. A foundational belief among voice therapists and laryngologists is that the skilled ear of a clinician and/or physician when used for auditory-perceptual assessment is a critical tool for the evaluation and management of voice disorders. Auditory-perceptual assessments, however, are by their nature subjective. They are prone to variability from one listener to the next, and perceptual thresholds for what constitutes a “normal” voice from a “dysphonic” voice, and the degree of dysphonic severity, also vary. These are among the reasons why instrumental assessments are also considered valuable and sometimes critical tools for the assessment and management of dysphonic patients.
Along with laryngeal endoscopy - the most important instrumental assessment applied to dysphonic patients - acoustic and aerodynamic assessments of vocal function provide information corresponding to underlying laryngeal physiology. The patterns of acoustic energy, airflow through the glottis, and pressures below the glottis are influenced by the neuromuscular coordination, configuration, and oscillatory movement of the vocal folds. Typically, when a voice changes from a perceptual state of normal to dysphonic or vice versa, the acoustic spectrum and underlying aerodynamic forces also change. Acoustic and aerodynamic assessments allow for objective measurement of these changes and are not influenced by the perceptual experience of a listener, potential perceptual bias, or the variability in perceptual calibration which affect auditory-perceptual assessments.
From its inception the Journal of Voice has been a primary repository of new and expanded knowledge of the acoustic and aerodynamic characteristics of normal and disordered voice production. Among the authors who have contributed to these publications include internationally recognized leaders in clinical voice science and practice across more than four decades. The articles included in this compendium relate to both the speaking and singing voice in normal and disordered states. While page limitations do not allow for a complete reference of all articles published in this journal, the following collection of historical publications include those which have expanded our understanding of acoustic and aerodynamic characteristics of voice in a majority of the treatment-seeking and non-treatment seeking populations served by speech-language pathology and medicine.
Across the volumes included in this collection the reader will find articles illuminating knowledge of acoustic and aerodynamic expectations in (a) normal voice production, (b) vocal development in children, (c) non-organic voice disorders, (d) vocal aging, (e) mid-membranous lesions, (f) vocal fold paralysis, (g) spasmodic dysphonia and essential voice tremor, and many other conditions causing dysphonia. In addition, the articles identified in this collection include many which have helped us understand how the larynx controls and is affected by singing. Many of these articles have also provided evidence of how the singing voice responds to medical and behavioral treatment, and the effectiveness of different voice therapy and surgical interventions for varied etiologies of dysphonia.
In reviewing this collection it would be reasonable to suggest that the Journal of Voice has served as the preeminent source for scientific evidence related to clinical voice science for the past thirty years. Articles published in this journal continue to inform evidence-based practice and enlighten knowledge of the human speaking and singing voice. It is my hope that this collection provides a resource for professionals in addition to stimulating ideas for future research. It has been a rewarding experience trolling through the past issues of this journal, and it is my hope that the reader will find value in this robust collection of knowledge associated with acoustic and aerodynamic assessments of voice.
Christopher R. Watts, Ph.D., CCC-SLP
Director, Davies School of Communication Sciences & Disorders
Texas Christian University
Fort Worth, TX