Effects of a vocally fatiguing task and systemic hydration on phonation threshold pressure

Phonation threshold pressure (PTP), effort for speaking, and vibratory closure pattern were assessed in 4 women with normal untrained voices after 2 hours of loud reading. PTP generally increased after this vocally fatiguing task at conversational pitch and 10%, 50%, and especially 80% of the pitch range. Increased systemic hydration by drinking water appeared to attenuate and/or delay the elevation of PTP for 3 subjects, at least at the highest pitch tested. Effort for speaking increased consistently throughout the loud reading task and subsequently decreased after 15 minutes of vocal silence. Upon videostroboscopic examination of the larynx, 3 subjects demonstrated spindle-shaped vibratory closure patterns on occasion after loud reading. The results provide preliminary support for increasing water consumption to reduce or delay some vocal-function changes after prolonged loud phonation in untrained speakers.     

Perceived phonatory effort and phonation threshold pressure across a prolonged voice loading task: a study of vocal fatigue

Although the problem of vocal fatigue is not uncommon in people with voice disorders, research on objective quantifiable indicators of vocal fatigue is limited. It has been suggested that a speaker's perception of increased phonatory effort associated with periods of prolonged voice use is related to increased lung pressure required to initiate and sustain phonation. The purpose of this study was to examine the relationship among perceived phonatory effort (PPE), which was used as a subjective index of vocal fatigue, and phonation threshold pressure (PTP), a quantifiable measure defined as the minimal lung pressure required to initiate and sustain vocal fold oscillation. PTP and PPE were recorded before, during, and after five adult male and five adult female speakers engaged in a prolonged oral reading task designed to induce vocal fatigue. The results supported a direct, moderately strong relationship between PTP and PPE, particularly when PTP was measured during speech produced at comfortable and low-speaking pitch levels. No gender effects were found. PTP returned to baseline levels within 1 hour after the fatiguing task. PPE returned to baseline within 1 day. The data support the use of PTP as an objective index of vocal fatigue.     

Effect of Fasting on Voice in Women

OBJECTIVE/HYPOTHESIS: To study the effect of fasting on voice in women: abstinence from food and water intake between 14 and 18 hours. STUDY DESIGN: A prospective study on female subjects. MATERIAL AND METHOD: A total of 28 female subjects were included in this study. Their age ranged between 21 and 45 years. Subjects with vocal symptoms or vocal fold lesions were excluded. The subjects were tested when they were not fasting and while fasting after the first week of intermittent fasting during Ramadan. Each subject was first asked about her vocal symptoms and the ease of phonation or phonatory effort. Then each underwent acoustic analysis and laryngeal video-endostroboscopy. RESULTS: Vocal fatigue was the most common reported complaint (53.6%) followed by deepening of the voice (21.4%) and harshness (10.2%). Self-reported phonatory effort was significantly affected by fasting (P value < 0.001). Out of the 28 subjects, 23 had an increase in their phonatory effort. Vocal acoustic parameters did not change markedly except for the maximum phonation time, which decreased significantly. Laryngeal video-endostroboscopy did not reveal any significant changes during fasting. All stroboscopic parameters were the same except for a decrease in the amplitude of the mucosal waves in one subject and the presence of a posterior chink in three subjects. CONCLUSION: Fasting affects voice. There is an increase in the phonatory effort, and vocal fatigue is the most common symptom.     

Documenting laryngeal change following prolonged loud reading: A videostroboscopic study

This study investigated the effects of prolonged loud reading on trained and untrained subjects. Subjects were eight young women singers, and eight young women with limited musical experience. Each subject underwent videostroboscopic examination prior to and following 1 h of prolonged loud reading. The pretest and posttest videotaped samples were randomized and presented to three experienced judges, who evaluated various aspects of laryngeal appearance and vibratory characteristics. Analyses of group data revealed that untrained subjects showed a small but significant increase in amplitude of vocal fold excursion following the experimental task. No significant differences were noted in the trained singer group. When individual variation was analyzed, it was found that most subjects did not show many changes from pretest to posttest. It was concluded that a l-h loud-reading task was not sufficient to induce notable laryngeal alterations     

Laryngeal function and vocal fatigue after prolonged reading in individuals with unilateral vocal fold paralysis

The purpose of the present study was to examine the effect of prolonged loud reading, intended to induce fatigue, on vocal function in adults with unilateral vocal fold paralysis (UVFP). Subjects were 20 adults, 37–60 years old, with UVFP secondary to recurrent laryngeal nerve paralysis. Subjective ratings and instrumental measures of vocal function were obtained before and after reading. Statistical analysis revealed subjects rated their vocal quality and physical effort for voicing more severely following prolonged loud reading, whereas expert raters did not detect a significant perceptual difference in vocal quality. Reading fundamental frequency (Fo) was significantly increased following prolonged loud reading, as were mean airflow rates at all pitch conditions. Maximum phonation times for comfort and low pitches significantly decreased during posttests. Multiple regression analyses revealed significant associations between ratings of posttest physical effort and select posttest measures. Interpretation of results indicates the prolonged loud reading task was successful in vocally fatiguing most of the UVFP subjects. Key physiologic correlates of vocal fatigue, in individuals with UVFP, include further reduction of glottic efficiency, resulting in decreased regulation of glottic airflow and a temporary destabilization of speaking fundamental frequency.     

An evaluation of the effects of three laryngeal lubricants on phonation threshold pressure (PTP)

Clinicians frequently offer advice to performers and voice-disordered patients aimed ostensibly to manipulate the water content and/or viscosity of the mucus blanket covering the vocal folds. To evaluate the relative effects of three potential laryngeal lubricants on phonatory function (ie, water, Mannitol--an osmotic agent, and Entertainer's Secret Throat Relief (Kli Corp., Carmel, IN)--a glycerin-based product), phonation threshold pressure (PTP) was measured in 18 healthy, vocally normal female participants twice before (baseline) and then four times after 2 ml of each substance were nebulized. PTP is the minimum subglottal pressure required to initiate vocal fold oscillation, and the lowering of PTP is assumed to correspond to physiologically more efficient phonation and reduced phonatory effort. Over a 3-week period, participants were tested on three separate occasions (at 1-week intervals). On each occasion, a different nebulized treatment was administered. PTP for both comfortable and high fundamental frequency productions was measured using an oral pressure-flow system (Perci-Sars, MicroTronics Corp., Chapel Hill, NC). Analysis of the results revealed that Mannitol, an agent that encourages osmotic water flux to the luminal airway surface, lowered PTP immediately after its administration (ie, p = 0.071, for high-pitched productions only). However, the duration of its PTP lowering effect was less than 20 minutes. The other two substances did not demonstrate any significant postadministration effect on PTP.     

Loud Speech in Realistic Environmental Noise: Phonetogram Data, Perceptual Voice Quality, Subjective Ratings, and Gender Differences in Healthy Speakers

A new method for cancelling background noise from running speech was used to study voice production during realistic environmental noise exposure. Normal subjects, 12 women and 11 men, read a text in five conditions: quiet, soft continuous noise (75 dBA to 70 dBA), day-care babble (74 dBA), disco (87 dBA), and loud continuous noise (78 dBA to 85 dBA). The noise was presented over loudspeakers and then removed from the recordings in an off-line processing operation. The voice signals were analyzed acoustically with an automatic phonetograph and perceptually by four expert listeners. Subjective data were collected after each vocal loading task. The perceptual parameters press, instability, and roughness increased significantly as an effect of speaking loudly over noise, whereas vocal fry decreased. Having to make oneself heard over noise resulted in higher SPL and F0, as expected, and in higher phonation time. The total reading time was slightly longer in continuous noise than in intermittent noise. The women had 4 dB lower voice SPL overall and increased their phonation time more in noise than did the men. Subjectively, women reported less success making themselves heard and higher effort. The results support the contention that female voices are more vulnerable to vocal loading in background noise.     

Task complexity effect on vocal reaction time in aged speakers

The aged population is at risk for impaired speech communication due to the increased likelihood of deterioration of central nervous system (CNS) processes that underlie cognition, language, and/or speech motor control. Vocal reaction time (RT) may provide a means of quantifying the efficiency of CNS processes that underlie speech production. The present study used a simple RT paradigm to investigate effects of the complexity of the required task on vocal RT in normal young and aged speakers. Task complexity was represented by two levels: a single word and a short sentence. Only the aged subjects showed a significant task complexity effect on vocal RT. Furthermore, the between-group RT difference increased as a function of task complexity. Specific causes for the increase in vocal RT for the aged subjects are presently unknown, but likely reside in altered respiratory biomechanics and reduced efficiency of CNS motor processing.     

Effects of perceived listeners on speakers''vocal intensity

The purpose of this study was to determine the amount of change in speakers' vocal intensity when a listener is located at various perceived versus actual physical distances from a speaker. Twelve men and 12 women with normal voices were asked to read a passage at three interspeaker distances in one of two conditions. In the perceived listener condition, participants were asked to “imagine” that the listener was located 3, 15, or 30 ft away. In the actual listener condition, one of the experimenters stood at each one of the three experimental distances. Conditions were counterbalanced. The results showed that men and women increased vocal intensity levels for all three interspeaker distances regardless of the type of condition. However, women showed larger increases than men at all interspeaker distances in both conditions. Data for both men and women combined showed that the amount of increase is <6 dB, which indicates that speakers do not follow the inverse square law when raising vocal intensity. Clinical implications of the results are discussed.     

Oral breathing increases Pth and vocal effort by superficial drying of vocal fold mucosa.

Oral breathing superficially dehydrates the airway lumen by decreasing the depth of the sol layer in humans and animals. Conversely, nasal breathing can increase the humidity of inspired air. We compared the effects of short-term oral and nasal breathing on Pth and perceived vocal effort in 20 female subjects randomly assigned to two groups: oral breathing (N = 10, age 21-32 years); nasal breathing (N = 10, age 20-36 years). We hypothesized that short-term oral breathing, but not nasal breathing, would increase Pth, and that subjects would perceive this change as an increase in vocal effort. Following 15 minutes of oral breathing, Pth increased at comfortable and low pitch (p < 0.01) with 6 of 10 subjects reporting increased vocal effort. Nasal breathing reduced Pth at all three pitches (p < 0.01), and 7 of 10 subjects reported decreased vocal effort. Over all subjects, 49% of the variance in treatment-induced change in Pth was accounted for by change in vocal effort (R = 0.70). We posit that obligatory oral breathing places healthy subjects at risk for symptoms of increased vocal effort. The facilitatory role of superficial hydration on vocal fold oscillation should be considered in biomechanical models of phonation and in the clinical prevention of laryngeal dryness.