On the relation between the dimensions and resonance characteristics of the vocal tract: a study with MRI.

The relation between the spatial configuration of the vocal tract as determined by magnetic resonance imaging (MRI) and the acoustical signal produced was investigated. A male subject carried out a set of phonatory tasks, comprising the utterance of the sustained vowels /i/ and /a/, each in a single articulation, and the vowel /epsilon/ with his larynx positioned variously on a vertical axis. Two- and three-dimensional measurements of the vocal tract were performed. The results of these measurements were used to calculate resonance frequencies, according to predictions from acoustical theory. Finally, calculated frequencies were compared with actually measured resonance frequencies in the audio signal. We found a strong relation between the acoustical signal produced and the spatial configuration for the first resonance frequencies of the articulations of the vowel /epsilon/, and first two resonance frequencies of the vowels /a/ and /i/. The capability to determine accurately vocal tract dimensions is a major advantage of this imaging technique.

Cineradiography of the pharyngoesophageal segment in postlaryngectomy patients.

The use of tracheoesophageal voice prostheses has gained wide acceptance in the field of vocal rehabilitation after total laryngectomy. In a randomized study with 3 arms, alaryngeal speech proficiency was assessed in 60 postlaryngectomy patients: 20 patients underwent primary unilateral pharyngeal myotomy, 21 patients underwent neurectomy of the pharyngeal plexus in addition to pharyngeal myotomy, and 19 patients did not undergo an additional surgical procedure. Pharyngoesophageal (PE) dynamics were examined during esophageal and tracheoesophageal speech. A single vibrating PE segment was seen in good alaryngeal speakers. Hypertonicity, spasm, strictures, and hypotonicity of the PE segment were correlated significantly with poor or moderate alaryngeal speech. Unilateral myotomy with or without unilateral neurectomy prevented hypertonicity or spasm of the PE segment. The acquisition of alaryngeal speech did not differ significantly between the 2 groups who had undergone an additional surgical procedure. Evaluation of anatomic and physiological factors may be helpful in subsequent clinical management to achieve effective alaryngeal speech.

Deterioration of the Provox silicone tracheoesophageal voice prosthesis: microbial aspects and structural changes.

Device life of tracheoesophageal voice prostheses is limited due to deterioration of the polymers. A group of 55 postlaryngectomy patients fitted with a Provox voice prosthesis have been studied prospectively during 6 months. Thirty-seven prostheses were replaced due to a dysfunctional valve mechanism. Although colonization with Candida species was highly associated with destruction of the silicone material, other upper respiratory tract commensals, e.g. Staphylococcus aureus, were also demonstrated. Electron microscopy of the contaminated devices showed colonization and disruption of the silicone material by penetrating yeast hyphae. During the study a remarkable increase of intratracheal phonatory pressures was assessed with progressive colonization of the prostheses.

Suspension microlaryngoscopic surgery and indirect microlaryngostroboscopic surgery for benign lesions of the vocal folds.

A prospective study was designed to compare the effects on voice capacities after either suspension microlaryngoscopic surgery or indirect microlaryngostroboscopic surgery. Patients where the clinical diagnosis 'dysphonia due to a benign lesion of the vocal fold' was made, and who could be operated in either way, entered the study. Post-operative voice evaluation was performed on 21 patients after suspension microlaryngoscopic or indirect microlaryngostroboscopic surgery. The long-term voice results following indirect microlaryngostroboscopic surgery and suspension microlaryngoscopic surgery demonstrate a statistically significant improvement for the maximum intensity, maximum dynamic intensity range, dynamic intensity range at habitual speaking pitch, and melodic pitch range. In selected cases indirect microlaryngostroboscopic surgery offers a very good functional result.

Standardized laryngeal videostroboscopic rating: differences between untrained and trained male and female subjects, and effects of varying sound intensity, fundamental frequency, and age.

To determine the influence of the factors gender, vocal training, sound intensity, pitch, and aging on vocal function, videolaryngostroboscopic images of 214 subjects, subdivided according to gender and status of vocal training, were evaluated by three judges with standardized rating scales, comprising aspects of laryngeal appearance (larynx/pharynx ratio; epiglottal shape; asymmetry arytenoid region; compensatory adjustments; thickness, width, length, and elasticity of vocal folds) and glottal functioning (amplitudes of excursion; duration, percentage, and type of vocal fold closure; phase differences; location of glottal chink). The video registrations were made while the subjects performed a set of phonatory tasks, comprising the utterance of the vowel /i/ at three levels of both fundamental frequency and sound intensity. Analysis of the rating scales showed generally sufficient agreement among judges. With the exception of more frequently observed complete closure and lateral phase differences of vocal fold excursions in trained subjects, no further differences were established between untrained and trained subjects. With an alpha level of p = 0.005, men differed from women with respect to laryngeal appearance (larynx/pharynx ratio, compensatory adjustments, and the presence of omega and deviant-shaped epiglottises), and their vocal folds were rated thicker in the vertical dimension, smaller in the lateral dimension, longer, and more tense, with smaller amplitudes of excursion during vibration. Glottal closure in male subjects was rated more complete, but briefer in duration. Significant effects of the factors pitch, sound intensity, and age on vocal fold appearance and glottal functioning were ascertained. Awareness of the influence of these factors, as well as the factor gender, on the rated scales is essential for an adequate evaluation of laryngostroboscopic images.

Differences in phonetogram features between male and female subjects with and without vocal training.

Singing not only requires good voluntary control over phonation and a musical ear, it also demands certain capacities of the voice source. These capacities include a desirable range of sound intensity and frequency, which can be measured and represented in a phonetogram. The influence of specific factors on voice capacities may be ascertained by the analysis of phonetograms. To determine the influence of the factors gender and voice training, phonetograms of 224 subjects, subdivided accordingly into four groups, were analyzed in two different ways. One is based on the rescaling of phonetograms, whereas the other derives analytic variables from the features' shape, area, and dynamic range. Analysis showed that, regarding gender, male subjects are able to produce softer phonations, whereas female subjects produced louder phonations at specific parts of their comparable frequency ranges. Trained subjects have a larger enclosed area of the phonetogram, which is primarily based on extended soft voice capabilities in both genders and the significantly larger frequency range in trained female subjects. The shape analysis, performed with Fourier Descriptors, revealed differences for the factors gender and training.

Comparison of vocal tract formants in singing and nonperiodic 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.

Glottal volume velocity waveform characteristics in subjects with and without vocal training, related to gender, sound intensity, fundamental frequency, and age.

Glottal volume velocity waveform characteristics of 224 subjects, categorized in four groups according to gender and vocal training, were determined, and their relations to sound-pressure level, fundamental frequency, intra-oral pressure, and age were analyzed. Subjects phonated at three intensity conditions. The glottal volume velocity waveforms were obtained by inverse filtering the oral flow. Glottal volume velocity waveforms were parameterized with flow-based (minimum flow, ac flow, average flow, maximum flow declination rate) and time-based parameters (closed quotient, closing quotient, speed quotient), as well as with derived parameters (vocal efficiency and glottal resistance). Higher sound-pressure levels, intra-oral pressures, and flow-parameter values (ac flow, maximum flow declination rate) were observed, when compared with previous investigations. These higher values might be the result of the specific phonation tasks (stressed /ae/ vowel in a word and a sentence) or filtering processes. Few statistically significant (p < 0.01) differences in parameters were found between untrained and trained subjects [the maximum flow declination rate and the closing quotient were higher in trained women (p < 0.001), and the speed quotient was higher in trained men (p < 0.005)]. Several statistically significant parameter differences were found between men and women [minimum flow, ac flow, average flow, maximum flow declination rate, closing quotient, glottal resistance (p < 0.001), and closed quotient (p < 0.005)]. Significant effects of intensity condition were observed on ac flow, maximum flow declination rate, closing quotient, and vocal efficiency in women (p < 0.005), and on minimum flow, ac flow, average flow, maximum flow declination rate, closed quotient, and vocal efficiency in men (p < 0.01).

The effects of frequency and intensity level on glottal closure in normal subjects.

The degree of glottal closure during phonation has an influence on voice quality and it is related to the robustness of the voice source. To quantify glottal closure a frame of reference was created by investigating 47 healthy men and 92 healthy women with no vocal complaints using videolaryngostroboscopy. Observing recorded images the degree of glottal closure was rated with a percentage. Results indicate that men have better glottal closure than women (P < 0.001). An increase in vocal intensity is related to improved glottal closure (P < 0.001), and in women a negative relationship was established between pitch and glottal closure (P < 0.001). Normal glottal closure in men is a complete closure, whereas in women a closure of at least 90% should be attained. If these percentages cannot be established during loud phonation, it suggests the presence of a less robust larynx. To evaluate and quantify the function of the voice source, in clinical practice the larynx should not be observed at only one intensity level, but at a variety of intensity and frequency levels.

A structured approach to voice range profile (phonetogram) analysis.

A new method to analyze voice range profiles (phonetograms) is described. The structured analysis is based on quantitatively determining the features: shape, area, and "speaking range" dynamics, without distorting the shape of phonetograms. The parameter sets describing these features are calculated independently of fundamental frequency, which makes it possible to compare phonetograms. Two phonetograms representing a normal and a pathological example are used to illustrate the proposed method. The process provides a tool for establishing normative data for specified groups.

Longitudinal non-invasive perilymphatic pressure measurement in patients with Ménière's disease.

The homeostasis of inner-ear fluids is essential for the functions of hearing and equilibrium. Inner-ear disorders, such as Ménière's disease, are affected by inner-ear pressure. The displacement of the human tympanic membrane can be studied by means of the MMS-10 Tympanic Displacement Analyser (Marchbanks Measurement Systems Ltd., UK) and is thought to be a measure for perilymphatic pressure variations. This measurement was performed in 18 patients with Ménière's disease (20 affected ears) at regular intervals, in order to investigate possible pressure variations in relation to the following symptoms: hearing loss, vertigo, tinnitus and pressure sensation. Symptoms changed independently; changes in symptoms were not significantly related to changes in perilymphatic pressure, as measured by means of the MMS-10 analyser.