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A quantitative output-cost ratio (OCR) is proposed for objective use in voice production and is defined as the ratio of the acoustic output intensity to the collision intensity of the vocal folds. Measurement of the OCR is demonstrated in a laboratory experiment using 5 excised larynges and a transducer designed for use on human subjects. Data were gathered at constant fundamental frequency (150 Hz). Subglottal pressure was varied from 1.0 to 1.6 kPa, and glottal width at the vocal processes was varied from a pressed condition to a 2-mm gap. The OCR was plotted as a function of glottal width. With no vocal tract, the excised larynx experiments yielded a broad maxima in the OCR curves, across all subglottal pressure conditions, at about 0.6 mm. Computer simulations indicate that sharper maxima may occur when the influence of the vocal tract is taken into account. The potential clinical utility of the OCR is discussed for treatment of a wide range of voice disorders, including those involving both hyper- and hypoadduction. [ABSTRACT FROM AUTHOR]

The purpose of this study was to look at the effect of orolabial amplification on the intelligibility of speech spoken with a neck model electrolarynx for two distance conditions, three noise conditions, and in relative quiet. A speaker using a neck model electrolarynx read single-answer questions to six listeners. The questions were read with and without amplification at 1.5 and 2.5 m distance, in relative quiet as well as in 66 dB, 72 dB, and 76 dBSPL (A-weighted) prerecorded cafeteria noise. The results of the study showed that speech-to-noise ratios were improved for amplified speech, with improvement in intelligibility for speech spoken in moderate background noise (66 and 72 dBSPL). The effect of the "buzz" of the artificial larynx is reduced, and speakers are better understood in moderate background noise with this amplification system. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if pressed, normal, resonant, and breathy voice qualities can be distinguished from one another by laryngeal resistance (LR; cm H(2)O/l/s) and/or vocal efficiency (VE; dB/cm H(2)O x l/s) in vocally, trained subjects. The experimental design was a within-subjects repeated measures design. Independent variables were pressed, normal, resonant, and breathy voice qualities. Dependent variables were LR and VE. Participants were 13 women of age 18-45 years with established vocal expertise. After a brief training phase, subjects were asked to produce each of the voice qualities on the pitch A3 (220 Hz) at a constant, individually identified comfortable dB level (+/-1 dB), during a repeated consonant-vowel utterance of /pi pi pi pi pi/. Results indicated that LR but not VE reliably distinguished pressed, normal, and breathy voice. Neither of the measures, however, distinguished normal from resonant voice, which were distinguished perceptually. The results suggest that LR may provide a useful tool for studying the coordinative dynamics of pressed, normal, and breathy voice qualities.

The development of personalized medicine is a primary objective of the medical community and increasingly also of funding and registration agencies. Modeling is generally perceived as a key enabling tool to target this goal. Agent-Based Models (ABMs) have previously been used to simulate inflammation at various scales up to the whole-organism level. We extended this approach to the case of a novel, patient-specific ABM that we generated for vocal fold inflammation, with the ultimate goal of identifying individually optimized treatments. ABM simulations reproduced trajectories of inflammatory mediators in laryngeal secretions of individuals subjected to experimental phonotrauma up to 4 hrs post-injury, and predicted the levels of inflammatory mediators 24 hrs post-injury. Subject-specific simulations also predicted different outcomes from behavioral treatment regimens to which subjects had not been exposed. We propose that this translational application of computational modeling could be used to design patient-specific therapies for the larynx, and will serve as a paradigm for future extension to other clinical domains.

Despite the fact that vocal folds are subjected to extensive mechanical forces, the role of mechanical strain in vocal fold wound healing has been overlooked. Recent studies on other tissues have demonstrated that low physiological levels of mechanical forces are beneficial to injured tissues, reduce inflammation, and induce synthesis of matrix-associated proteins essential for enhanced wound healing. In this study, we speculated that mechanical strain of low magnitudes also attenuates the production of inflammatory mediators and alters the extracellular matrix synthesis to augment wound healing in cultured vocal fold fibroblasts. To test this hypothesis, fibroblasts from rabbit vocal folds were isolated and exposed to various magnitudes of cyclic tensile strain (CTS) in the presence or absence of interleukin-1beta (IL-1beta). Results suggest that IL-1beta activates proinflammatory gene transcription in vocal fold fibroblasts. Furthermore, CTS abrogates the IL-1beta-induced proinflammatory gene induction in a magnitude-dependent manner. In addition, CTS blocks IL-1beta-mediated inhibition of collagen type I synthesis, and thereby upregulates collagen synthesis in the presence of IL-1beta. These findings are the first to reveal the potential utility of low levels of mechanical signals in vocal fold wound healing, and support the emerging on vivo data suggesting beneficial effects of vocal exercise on acute phonotrauma.

Summary: The basic science of wound healing is largely omitted from the curriculum of many voice clinicians. This fact is relatively disheartening as most therapeutic manipulation in the realm of laryngology and voice disorders deals with injured tissue. Therefore, the selection of therapeutic tasks for persons with vocal injury should ideally be informed by basic science in wound healing. Recently, several investigators have initiated lines of research to determine the course of vocal fold wound healing and the potential role of therapeutic agents, including behavioral agents. The current review seeks to provide a foundation of basic wound healing science and present the most current data regarding the wound healing process in the vocal folds.

The application of topical anesthesia to the oropharynx is a common clinical practice during oral and nasal laryngoscopy. Clinically, questions have been raised about whether topical anesthesia alters laryngeal secretions, which distorts clinical impressions. A double-blind, placebo controlled design was employed to address this issue. Ten premenopausal women with healthy vocal folds and 10 premenopausal women with phonotraumatic lesions underwent oral videolaryngoscopic examinations on subsequent days under both anesthesia and placebo conditions, in counterbalanced order. Video segments were rated by three judges. Dependent variables were balling and pooling of secretions, as previously described in the literature. Statistical analyses failed to reveal any clear effect of topical anesthesia on either secretion balling or pooling for the collapsed data set, but one cannot exclude changes in individual cases. Moreover, there was no evidence that secretions were differentially affected by anesthesia across subject groups. Null results in this data set replicate and extend previously reported findings by other authors. An incidental but potentially interesting finding was that the order of treatment condition (anesthesia versus placebo first) seemed relevant for secretions: Subjects who received the anesthesia condition first tended to show more secretion balling in general, as compared with subjects who received the placebo condition first. Speculation is entertained regarding possible physiological pathways for these incidental findings, which could be relevant for some clinical practice.

Purpose: This study's broad objective was to examine the effectiveness of surface electromyographic (EMG) biofeedback for motor learning in the voice production domain. The specific objective was to examine whether concurrent or terminal biofeedback would facilitate learning for a relaxed laryngeal musculature task during spoken reading., Method: Twenty-two healthy adult speakers were randomly assigned to 1 of 2 groups. One group received real-time EMG waveform displays of muscle activation from bilateral thyrohyoid sites during reading trials (concurrent feedback group). The other group received static terminal EMG waveform displays about activation levels for the same sites on completion of successive trials (terminal feedback group). All participants were instructed to minimize EMG amplitudes from the thyrohyoid sites during phonation in an oral reading task. Signals were also collected from control, orofacial sites, but participants received neither instructions nor feedback for those sites., Results: The pooled data (2 feedback groups x 2 electrode sites) showed that, overall, muscle activation levels did decrease across baseline, training, and no-feedback test phases. However, no clear evidence was seen of reliable changes in the targeted laryngeal muscle activation levels across the phases, for either the concurrent or the terminal feedback groups. Paradoxically, and entirely unanticipated, reliable decreases were seen in muscle activation for the orofacial, no-feedback control sites. Those decreases were equivalent across concurrent and terminal feedback groups., Conclusions: The unanticipated findings indicate that the provision of biofeedback for a target muscle group facilitated incidental learning in another, untargeted muscle group. Discussion focuses on the possible role of locus of attention in motor learning. Building on literature from other domains, the hypothesis is advanced that attention to muscular contractile force during training trials may suppress intentional learning for attended target sites but may benefit incidental learning for nearby, unattended sites.

This study seeks to determine the ability of enzyme-linked immunosorbent assays (ELISAs) of vocal fold secretions to detect and describe the acute tissue response to injury in a rabbit vocal fold model. Vocal fold secretions were collected before the induction of a unilateral surgical injury to the vocal fold and at 6 timepoints after injury (1, 5, 7, 10, 14, and 21 days). Secretions were then subjected to ELISAs to assess concentrations of interleukin-1 beta (IL-1beta) and prostaglandin-E2 (PGE-2). The results indicate that ELISAs may be useful in documenting fluctuations in these markers associated with the wound healing process in the rabbit model. The temporal expression of both IL-1beta and PGE-2 was consistent with their proposed roles in the wound healing cascade in other systems, pointing to the potential that surface secretions may be at least partial indicators of wound healing events within the tissue.

Several authors have eloquently described the characteristics of vocal fold scar, a long-term consequence of vocal fold injury. However, events in the acute stage of mucosal injury, which lead up to fibrosis, have been largely overlooked. The current study describes acute events with regard to mucosal re-formation in a rabbit model. Vocal fold injury was induced surgically. A fibrinous clot was present 1 day after injury. Massive cellular infiltration was noted on day 3, and complete epithelial coverage was achieved by day 5. Also, neo-matrix deposition was noted as early as 5 days after injury, and more mature collagen was seen by day 7. The general timetable described in the current study can contribute to the experimental foundation for the development of regenerative models of healing in the vocal folds. Most notably, the proliferation phase of wound healing appears to occur approximately 3 days after injury, indicating a critical time for intervention. Manipulation and/or alteration of naturally occurring neo-matrix deposition and organization may yield improved biophysical function of the injured vocal fold.

This study seeks to determine the ability of enzyme-linked immunosorbent assays of vocal fold secretions to detect and describe the inflammatory response in the vocal folds. Vocal fold and palatal secretions were collected during operation from patients with a range of vocal fold disorders and from control patients. The secretions were subjected to assays for interleukin-1beta, prostaglandin E2, and transforming growth factor beta. The results indicate a differential expression of mediators associated with the wound healing cascade in the vocal folds. The prostaglandin E2 levels clearly differentiated vocal fold secretions associated with laryngeal disease versus control sites. Furthermore, the interleukin-1beta concentrations were significantly elevated in subjects with epithelial lesions of the vocal folds as opposed to lesions of the lamina propria. Although still in its infancy, such analysis may ultimately hold scientific and clinical utility in the study and management of patients with vocal fold disease.

The current study sought to determine whether shifts in key components of the inflammatory process could be detected from laryngeal secretions sampled before and after vocal loading. A healthy 44-year-old woman served as the subject. The vocal folds were swabbed to collect baseline secretions. Ten and 20 minutes after nearly constant loud phonation for 1 hour, the vocal folds were swabbed again. The findings indicated strong shifts in several key inflammatory mediators: interleukin-1beta, tumor necrosis factor alpha, and matrix metalloproteinase 8. The concentrations of those mediators continued to increase from the 10- to 20-minute postloading time-points. Transforming growth factor beta and prostaglandin E2 did not demonstrate clear shifts. In summary, mediators reflecting the acute inflammatory process could be detected from laryngeal secretions in an awake human. The upward slope of the curves at the 20-minute time interval indicates the need for longer follow-up sampling to determine the full biological response of the vocal folds to acute phonotrauma.

Four vocally untrained healthy adults, 2 men and 2 women, completed the study. A double-blind placebo-controlled approach was used to administer three treatments to each participant on separate days. Drugs treatments involved a single 60-mg dose of a diuretic, Lasix (LA), on one day, and a single 50-mg dose of an oral antihistamine, diphenhydramine hydrochloride (DH), on another day. A third day involved the administration of a placebo, sugar pills (SP). Critical posttreatment measures were weight (kg), which estimated systemic dehydration, saliva viscosity (centipoise), which estimated secretion dehydration, and phonation threshold pressure (PTP, in cm H2O), at high pitches, which indicated pulmonary drive for phonation. The central experimental question was: Does systemic dehydration, or secretory dehydration, or both, mediate increases in PTP that are known to occur following dehydration treatments? The results showed that LA induced systemic dehydration, as shown by a decrease in total body mass of about 1%. Weight losses were seen during a 1- to 4-hour block following drug administration and persisted for at least 8 hours thereafter. PTPs also increased in that condition, about 23% relative to baseline, but only several hours after whole-body dehydration was initially seen (5-12 hours after drug administration). In contrast, no evidence was seen that DH accomplished either secretory dehydration or PTP shifts. The results indicate that systemic dehydration can mediate PTP increases. The influence of secretory dehydration on PTP is unclear.

Objective, quantitative information is lacking in the medical community about actual working conditions for professional singers onstage, and moreover, about which conditions are safe. Physicians, speech-language pathologists, and speech scientists focusing on laryngology should have relevant information about the opera as workplace and the medical sequelae of unhealthy environments. We describe five toxic substances to which singers presenting to our clinics were exposed while working professionally on the opera stage: (1) aromatic diisocyanates, (2) penicillium frequentans in cork granulate, (3) formaldehyde in cork granulate, (4) cobalt and aluminum (pigment components), and (5) quartz sand capable of entering the alveolae. Biological considerations and clinical data for some subjects suggest a direct causal link between the exposures and the patients' complaints and findings. Our observations suggest that whenever singers complain about deleterious conditions such as dry and hot onstage climate or suspicion of the presence of harmful substances, the specific conditions existing in the theater in question should be investigated. Harmful substances are not only poorly tolerated by singers, but also they should be preventable.

Vocal fold impact stress (force/area) has been implicated as a factor possibly contributing to the formation of nodules and polyps. The force of impact of a moving body is related to its acceleration. Since the mass of the folds is relatively constant, one expects impact force to be directly proportional to acceleration. A measure that reflects the relative displacement of the vocal folds is photoglottography (PGG). The velocity and acceleration of the folds are easily obtained by calculating the first and second derivatives of the PGG displacement waveform. This study, therefore, compared the second derivative of the PGG signal with simultaneously measured impact stress in an excised canine larynx model. Glottal transillumination (PGG) was measured with a subglottic transducer. A miniature force transducer placed in the midline between the vocal folds measured impact stress at the midglottal position. For nine different larynges, there was a positive and linear relationship between the second derivative of PGG and impact stress. The statistically significant results support the hypothesis that the second derivative of PGG m ay provide a use fulnoninvasive way to estimate relative vocal fold impact stress.

The purpose of this paper is to provide a cohesive review of the literature regarding the functional consequences of voice problems and occupational risk factors for them. The salient points are as follows. According to conservative estimates, approximately 28,000,000 workers in the US experience daily voice problems. Many people who experience voice problems perceive them to have a negative impact on their work and their quality of life. Estimates based on empirical data suggest that, considering only lost work days and treatment expenses, the societal cost of voice problems in teachers alone may be of the order of about $2.5 billion annually in the US. In fact, across several countries, "teacher" consistently emerges as the common occupation most likely to seek otorhinolaryngological (ORL) evaluation for a voice problem. Other occupational categories likely to seek ORL examination for a voice problem are singer, counselor/social worker, lawyer, and clergy. Finally, US Census data indicate that keyboard operators may be at special risk for voice problems because of a near-epidemic growth of repetitive strain injury (RSI), which can adversely affect the voice especially when speech recognition software is implemented. This paper discusses frequency data, quality of life data, and treatment considerations for these voice-related occupational issues.

The effects of exposure to dry air on phonation were measured in an ex vivo model of vocal fold vibration. Excised canine larynges were mounted on an apparatus and made to phonate at a constant subglottal pressure by means of unhumidified airflow. The phonation threshold pressure (PTP), glottal airflow, sound intensity of the acoustic output, and effects on vocal efficiency were also assessed. Student's t-test was performed on the results. In 17 larynges, the average PTP increased from 10.0 cm H2O to 15.0 cm H2O after exposure to dry airflow (p < .001). In addition, the average flow increased from 585 mL/s to 801 mL/s at a constant suprathreshold subglottal pressure (p < .001), and from 323 mL/s to 610 mL/s at the PTP (p < .001). The average acoustic output levels, measured during stable phonation segments, markedly decreased with exposure to the dry airflow, from 91.5 dB to 88.5 dB (p < .001). The average vocal efficiency decreased from 3.63 x 10(-4) to 7.00 x 10(-5) (p < .001). No such changes were seen in control larynges phonated with 100% humidified air used for driving the airflow. The results support previously reported modeling and experimental findings that dehydration of the vocal fold generally degrades laryngeal performance.

Singers and actors frequently complain about dusty and dry theater environments, which they believe induce respiratory tract indispositions and decrements in vocal performance. In the literature to date, extremely few quantitative data exist about actual climatic conditions on stage. A previous study by our group in an unhumidified theater found that it had too high temperatures, too dry and too dusty air, based on German occupational guidelines for the generic workplace. In the present study, humidification units were installed in the same theater, and the environmental measures were repeated. The primary findings indicated that, following the activation of the humidification units, temperatures, humidities and fine dust concentrations were improved and generally within acceptable ranges for the generic workplace, although not always optimal. Where unacceptable performance environments exist, special care should be taken to counsel performers with regard to possible prophylactic measures such as individual steam inhalation and fluid intake.

The primary question in this study was whether subjects with nodules and subjects with healthy larynges would produce "resonant voice" with a similar laryngeal configuration. A second question regarded whether the electroglottographic closed quotient (EGG CQ) could be used to noninvasively distinguish resonant from other voice types. Twelve adult singers and actors served as subjects, including 6 persons with healthy larynges and 6 persons with nodules. Performers were used as an attempt to maximize token validity and stability. Subjects produced repeated tokens of resonant, pressed, normal, and breathy voice during sustained vowels. Laryngeal adduction was directly estimated using blinded, ordinal, visual-perceptual ratings based on videoscopic views of the larynx. EGG CQs were further calculated based on separate trials. The perceptual ratings indicated that subjects in both groups produced resonant voice with a barely adducted or barely abducted laryngeal configuration that was distinct from configurations for pressed and breathy (but not normal) voice. Previous literature suggests that this configuration may be relevant in many cases of voice therapy (1). Average CQs distinguished resonant from pressed voice, but inconsistently distinguished resonant from breathy voice. Further CQs were reliably different across healthy subjects and subjects with nodules. Thus, the utility of this measure to noninvasively estimate resonant voice may be limited, particularly without ongoing subject-specific calibration procedures.

A professional singer with laryngeal granuloma underwent surgery following failed response to conservative treatments. Two primary findings emerged. First, although a sizable lesion was present initially, presurgical voice measures were largely normal or superior. The exception was elevated phonatory effort during singing. Second, postsurgical voice functions were entirely normal or superior (including phonatory effort), despite demanding singing performances a few weeks following surgery. The results add to the limited corpus of quantitative, normative-referenced data on voice in patients with granulomas and are inconsistent with previous reports of voice abnormalities in such patients and poor functional response to surgery.

In this study, a double-blind placebo-controlled approach was used to assess the relation between hydration level and phonatory effort. Twelve adult, untrained voice users with normal voices participated as subjects. Each subject received a 4-hour hydration treatment, a 4-hour dehydration treatment, and a 4-hour placebo (control) treatment. Following each treatment, phonatory effort was measured with a physiological measure, phonation threshold pressure (PTP), and with a psychological measure, direct magnitude estimation of perceived phonatory effort (DMEPPE). Summarizing the results across these measures, the findings indicated an inverse relation between phonatory effort and hydration level, but primarily for high-pitched phonation tasks. The findings for PTPs replicated those from an earlier study conducted without double-blind experimental manipulations (Verdolini-Marston, Titze, & Druker, 1990). Theoretical discussion focuses on the possible role of vocal fold tissue viscosity for hydration and dehydration effects, although direct measures of tissue viscosity are lacking.