Regulation of phonatory efficiency by vocal fold tension and glottic width in the excised canine larynx

Aerodynamic Parameters in Byzantine Chant Voices: Comparisons Across Pitch and Loudness

OBJECTIVE

This study was designed to assess the impact of phonation frequency and loudness increase on aerodynamic parameters of the singing voice in Byzantine chant (BC).

DESIGN

Aerodynamic measurements in BC were obtained and statistically analyzed.

METHOD

Fifteen experienced BC chanters, all baritones, performed the ascending notes G2, C3, E3, G3, C4, E4, and G4, at normal and high levels of loudness within a mask, while repeating strings of /pi/ syllables. The parameters of airflow (FR), subglottal pressure (Psub), and sound pressure level (SPL) were directly measured, and from them, the glottal flow resistance (Rg) and vocal efficiency (VE) were calculated. All the parameters' values were statistically analyzed.

RESULTS

Statistically significant differences for FR, Psub, and SPL parameters in BC between the two loudness levels, at constant pitch, and for Psub, SPL, Rg, and VE among different pitches, at constant loudness levels were detected. When loudness increases, a) only the mean values of FR, Psub, and SPL, within C3-C4, increase, whereas those of Rg and VE do not show any change, and b) at G2, only the mean Psub increases, while in the upper range E4-G4, both mean SPL and mean VE decrease. When pitch is raised, a) for each level of loudness, within G2-E4 pitch range, the means of Psub, SPL, Rg, and VE increase while this is not the case for FR, and b) in the highest range (E4-G4), average SPL and VE drop while Rg and Psub remain stable. Our findings suggest that: a) most participants increase Psub and SPL without modification of Rg when loudness increases, and b) most participants increase both SPL and Psub while changing Rg with pitch rise. Idiosyncratic differences among the participants were detected in Rg and Psub, because of pitch rise, and, also, in Rg and VE due to loudness increase.

CONCLUSIONS

The results from this study reveal that, within the C3-C4 pitch range: a) there is independent control between the loudness and glottal adduction, and b) Psub is the main tool for increasing both the loudness and SPL. For some exceptions among the participants, either the Rg alteration or other modifications of the vocal system are, possibly, the cause of the loudness increase. The increased mean values of SPL, Rg, and Psub with pitch rise, for most participants, suggest that both glottal adduction and Psub increase together with the SPL and pitch increase. The VE increase within G2-E4 pitches reaches a maximum value at E4. Some exceptions among the participants exist that suggest the possible use of different phonatory strategies when changing either the pitch or the vocal loudness.

Voice Quality Changes Following Phonatory-Respiratory Effort Treatment (LSVT®) Versus Respiratory Effort Treatment for Individuals with Parkinson Disease

Perceptual ratings of hoarseness and breathiness were used to assess the efficacy of two intensive methods for treating dysarthrophonia in individuals with idiopathic Parkinson disease. One method emphasized phonatory-respiratory effort (the Lee Silverman Voice Treatment, LSVT) and the other emphasized respiratory effort alone (RET). Perceptual ratings were performed by two expert listeners based on random order presentation of the patients' pretreatment and posttreatment recordings of the "Rainbow Passage." The listeners were blinded to the patients and their treatment group. Statistically significant pretreatment to posttreatment improvement in hoarseness and breathiness was observed in the LSVT group but not in the RET group. The present findings are consistent with acoustic and physiologic findings reported previously, providing further evidence for the efficacy of the LSVT.

Combination thyroplasty and the "twisted larynx:" combined type IV and type I thyroplasty for superior laryngeal nerve weakness

Vocal cord medialization through Isshiki type I thyroplasty is part of the standard approach for patients with unilateral vocal cord immobility secondary to recurrent laryngeal nerve paralysis. However, several other modalities have been used to treat the symptomatic "twisted" larynx caused by unilateral superior laryngeal nerve weakness. The Isshiki type IV thyroplasty (cricothyroid approximation) specifically addresses cricothyroid muscle weakness, but, canine studies at the Mayo Clinic demonstrated a trend toward decreased acoustic power and sound intensity with simulated cricothyroid activity. Thus it is reasoned that addition of an ipsilateral type I thyroplasty should help compensate for this power loss. Using videostroboscopic and acoustic analysis, 9 patients with unilateral superor laryngeal nerve weakness were treated with combination type IV and type I thyroplasty. Subjective dysphonia and objective visual and acoustic measurements revealed postoperative improvement in most patients. The combination type IV and type I thyroplasty is recommended for surgical treatment of patients with superior laryngeal nerve weakness, because it addresses cricothyroid muscle weakness without compromising vocal power.

Unilateral vocal fold paralysis: a review of the current methods of surgical rehabilitation

This review article discusses the surgical treatment of patients suffering from unilateral vocal fold paralysis who have already been assessed and considered appropriate candidates for surgery. There are currently three main methods of surgical rehabilitation; injection medialisation; laryngeal framework surgery; re-innervation procedures.

The role of stroboscopy in the management of a patient with a unilateral vocal fold paralysis

Stroboscopy is well established as an essential diagnostic tool in the assessment of the vocal folds during phonation. This paper analyses the stroboscopic findings in 100 patients with a unilateral vocal fold paralysis. Reliable stroboscopic signals were only obtained in patients with the paralysed fold close to the midline. These patients seldom require surgery however, usually responding to speech therapy with laryngeal compensation giving a good voice. Most patients that require surgery have a large glottal deficiency, but in this series these patients did not give an adequate signal for analysis. Although useful in the assessment of the muscle tone of the paralysed fold, the influence of stroboscopy on the surgical treatment in this series was limited.