Behavior of laryngeal muscles of the late William Vennard

Behavior of the cricothyroid, lateral cricoarytenoid, vocalis, and interarytenoid muscles of William D. Vennard was electromyographically investigated. This article demonstrates electromyographic recordings that have not been published. Data presentation and discussion are focused on vocal registers, some phrases for voice training and warm-up, vowels, phonation modes, fundamental frequency control, the interarytenoid muscle, and some nonsinging behaviors     

Open and covered singing as studied by means of fiberoptics, inverse filtering, and spectral analysis

Covering the voice near the passaggio is a technique mainly used in male classic Western singing. The purpose is said to be to smooth the register transition and avoid register breaks. The physiological and acoustical differences between open and covered singing near the so-called passaggio were investigated by means of fiberoptics, inverse filtering, and spectral analysis. The study corroborated previous findings that covering physiologically means a widening and lengthening of the pharynx. Acoustically, covering implies a change of formant frequencies, and an elevated sound pressure level of the lowest source spectrum partial, i.e., the fundamental, resulting from an increased transglottal air flow. The findings indicate that covered singing also is associated with larynx lowering. Covered singing near the passaggio shows similarities to so-called phonation, and is probably preferable from the point of view of vocal hygiene.     

Comparison of vocal tract formants in singing andnonperiodic phonation

The skilled use of nonperiodic phonation techniques in combination with spectrum analysis has been proposed here as a practical method for locating formant frequencies in the singing voice. The study addresses the question of the degree of similarity between sung phonations and their nonperiodic imitations, with respect to both frequency of the first two formants as well as posture of the vocal tract. Using magnetic resonance imaging (MRI), linear predictive coding (LPC), and spectrum analysis, two types of nonperiodic phonation (ingressive and vocal fry) are compared with singing phonations to determine the degree of similarity/difference in acoustic and spatial dimensions of the vocal tract when these phonation types are used to approximate the postures of singing. In comparing phonation types, the close similarity in acoustic data in combination with the relative dissimilarity in spatial data indicates that the accurate imitations are not primarily the result of imitating the singing postures, but have instead an aural basis.     

Changes in sustained production tasks among women with bilateral vocal nodules before and after voice therapy

The purpose of the current study was to determine how maximum phonationduration (MPD) of five notes (C4, D4, E4, F4, 134) sustained on /o/, sustained vowels (/i/, //, /a/, /u/), and s/z ratio (sustained /s/ and /z/ changed during voice therapy for vocal nodules. Voices of adult females before treatment and after resolution of vocal nodules were analyzed via the PM Pitch Analyzer. Treatment included tension reduction, abuse identification and elimination, laryngeal strengthening, and home exercises. Results indicate there was no significant difference in maximum phonation duration or S/Z ratio before and after treatment. Results revealed that females with vocal nodules demonstrate measurements before therapy similar to measures considered to be normal in persons without vocal nodules. Application of findings to clinical practice is discussed.     

Decomposition of Vocal Cycle Length Perturbations into Vocal Jitter and Vocal Microtremor, and Comparison of Their Size in Normophonic Speakers

A statistical method that enables raw vocal cycle length perturbations to be decomposed into perturbations ascribed to vocal jitter and vocal tremor is presented, together with a comparison of the size of jitter and tremor. The method is based on a time series model that splits the vocal cycle length perturbations into uncorrelated cycle-to-cycle perturbations ascribed to vocal jitter and supra-cycle perturbations ascribed to vocal tremor. The corpus was composed of 114 vocal cycle length time series for sustained vowels [a], [i], and [u] produced by 22 male and 16 female normophonic speakers. The results were the following. First, 100 out of 114 time series were decomposed successfully by means of the time series model. Second, vocal perturbations ascribed to tremor were significantly larger than perturbations ascribed to jitter. Third, the correlation between vocal jitter and vocal tremor was moderate, but statistically significant. Fourth, small but statistically significant differences were observed among the three vowel timbres in the relative jitter and the arithmetic difference of jitter and tremor. Fifth, the differences between male and female speakers were not statistically significant in the relative raw perturbations, the relative jitter, or the modulation level owing to tremor.     

Examination of air usage during phonation: Correlations among test parameters

Correlations among parameters indicating air usage during phonation were investigated in 60 normal subjects and 1,545 voice patients. The parameters examined were maximum phonation time (MPT), mean air flow rate for maximum sustained phonation (MFRm), mean air flow rate for comfortable phonation (MFRc), and phonation quotient (PQ). In normal subjects, correlations among MPT, MFRm, and PQ were high, but those between MFRc and the others were moderate. In cases of paralysis and hypofunctional dysphonia, all correlations between the four parameters were high. In the cases of polyp, nodule, epithelial hyperplasia, glottic carcinoma, and hyperfunctional dysphonia, the correlation between MPT and MFRc was moderate or not significant. The low correlation between these parameters was associated with the variations in flow rate differences between maximum and comfortable phonations. The results suggest that measurement of all four parameters is not necessary in routine tests and that MPT and MFRc should be measured in most voice patients.     

Characteristics of Phonatory Function in Singers and Nonsingers With Vocal Fold Nodules

Purpose

The goals of this study were to determine if there were significant differences between singers and nonsingers in the morphology of vocal nodules and the associated impact on vocal function.

Method

Participants were 10 professionally trained singers with nodules, eight nonsingers with nodules, and 10 individuals with healthy normal voice (controls). Surface electromyography (sEMG) from three anterior neck locations and acoustic rise times for vowels /a/ and /i/ were measured in all the participants. In individuals with nodules, dB SPL/cm H₂O, glottal airflow, and nodule location and size were also measured.

Results

There were no significant differences between singers and nonsingers with nodules in terms of airflow, dB SPL/cm H₂O, nodule size, or nodule location. In nonsingers with nodules, airflow and nodule size were significantly correlated, but were not significantly correlated in singers. Vowel rise times and sEMG during vocal tasks did not differentiate among nodule and control groups. Sternocleidomastoid sEMG during initiation of the vowel /a/ was statistically significantly stronger in nonsingers with nodules relative to singers with nodules and controls.

Conclusions

Nodule morphology did not differ between singers and nonsingers, although some behavioral aspects of phonation differed between the groups.     

The effects of excessive vocalization on acoustic and videostroboscopic measures of vocal fold condition

Although dysphonia is a recognized consequence of acute vocal abuse, associated changes in vocal fold appearance and function are not well understood. To document these presumed effects of vocal abuse, audio recordings of sustained vowel production were obtained from 42 drill sergeants daily during the first 6 days of a vocally demanding training exercise. Acoustic analysis showed abnormal levels of jitter and shimmer on Day 1 in 16 of the 42 subjects. Considering only the 26 subjects who showed normal voice acoustics on Day 1, the median levels of jitter and shimmer varied little over the course of training, and significant increases in jitter and shimmer were not seen during the study period. However, the distributions for both jitter and shimmer became more positively skewed and showed a greater number of positive outliers over the course of training. This trend was attributed to 11 subjects who showed two or more instances of abnormal voice acoustics over Days 2 through 6. Laryngeal videostroboscopic recordings of sustained vowel production also were obtained prior to and following training. Perceptual ratings of these recordings by 2 observers revealed significant increases in vocal fold edema, erythema, and edge irregularity, and decreases in vocal fold mucosal wave and amplitude of excursion following the 5-day training period. In general, there was considerable intersubject variability in the extent of acoustic and videostroboscopic effects over the course of training. Of the two types of data, videostroboscopy appears to provide a more sensitive indication of the effects of excessive vocalization.     

Vocal Process Avulsion

Vocal process avulsion is a rare condition in which laryngeal trauma causes a separation of the vocal process from the body of the arytenoid cartilage. Typically symptoms are dysphonia and shortness of breath during phonation. Strobovideolaryngoscopy, laryngeal electromyography, and laryngeal computed tomography are helpful in establishing this important and sometimes elusive diagnosis. Several treatment modalities have been reported with varying success. We report four new cases, review four cases reported previously by the senior author, and suggest approaches to diagnosis and optimal treatment of vocal process avulsion.     

Vertical laryngeal position: Research findings and application for singers

Research on vertical laryngeal position (VLP) is sparse, but shows that singers with classic vocal training maintain a VLP at or below a resting level. Untrained singers typically position their larynx higher as pitch increases, usually to a level well above the rest position. It has been shown that the larynx moves vertically by muscular forces and not by aerodynamic pressures. It appears that maintaining a low VLP during singing results in (1) facilitating a vocal fold vibratory pattern that produces substantial energy in the higher portion of the spectrum, (2) opening of supraglottal resonators, (3) easing of register transitions, and (4) reducing the magnitude of vocal fold closure forces.     

Phonation Threshold Pressure Across the Pitch Range: Preliminary Test of a Model

This study sought to examine the specific relationship between phonation threshold pressure (PTP) and voice fundamental frequency (F(0)) across the pitch range. A published theoretical model of this relationship described a quadratic equation, with PTP increasing exponentially with F(0). Prospective data from eight adults with normal, untrained voices were collected. Subjects produced their quietest phonation at 10 randomly ordered pitches from 5% to 95% of their semitone pitch range at 10% intervals. Analysis included curve fitting for individual and group data, as well as comparisons to the previous model. The group data fit a quadratic function similar to that proposed previously, but the specific quadratic coefficient and constant values differed. Four of the individual subjects' data were best fit by quartic functions, two by quadratic functions, and one by a linear function. This preliminary study indicates that PTP may be minimal at a "comfortable" pitch rather than the lowest pitch tested, and that, for some individuals, PTP may be slightly elevated during the passaggio between modal and falsetto vocal registers. These data support the general form of the theoretical PTP-F(0) function for these speakers, and indicate the possibility of potential refinements to the model. Future studies with larger groups of male and female subjects across a wider age range may eventually reveal the specific nature of the function.     

Vocal fold augmentation with injectable calcium hydroxylapatite: short-term results.

Symptoms of unilateral vocal fold paralysis are improved significantly by augmenting the paralyzed vocal fold via vocal fold injection. In this trial, augmentation with a new calcium hydroxylapatite implant was evaluated. In addition, two different phonosurgical injection techniques were used, and these procedures were compared for accuracy and reliability. A total of 11 terminal patients with unilateral vocal fold paralysis underwent vocal fold injection with calcium hydroxylapatite. Efficacy of the implant was evaluated by comparing results from the Voice Handicap Index (VHI) and mean airflow measurements before and 6 months after injection. Surgeon evaluations determined the comparative benefits of either endoscopic direct vocal fold injection or percutaneous vocal fold injection. Six-month data were obtained for a cohort of five patients. VHI scores improved for all five patients available for full evaluation and four of the five achieved improvements in mean airflow rates. Of the remaining patients, one later had a medialization laryngoplasty, two died from their terminal diseases before the 6-month follow-up, and two of the remaining three reported satisfaction with the results via telephone follow-up. Vocal fold injection via endoscopic, direct laryngoscopy was found to be a more reliable procedure for vocal fold injection than percutaneous injection. Slight overinjection (10% to 15%) was found to provide optimum results. Vocal fold injection of calcium hydroxylapatite for unilateral vocal fold paralysis improved voice quality and reduced mean airflow rates in this patient group with short-term results. Long-term studies are needed to confirm the durability of these findings.