Harm K. Schutte

Videokymography: High-speed line scanning of vocal fold vibration

A digital technique for high-speed visualization of vibration, called videokymography, was developed and applied to the vocal folds. The system uses a modified video camera able to work in two modes: high-speed (nearly 8,000 images/s) and standard (50 images/s in CCIR norm). In the high-speed mode, the camera selects one active horizontal line (transverse to the glottis) from the whole laryngeal image. The successive line images are presented in real time on a commercial TV monitor, filling each video frame from top to bottom. The system makes it possible to observe left-right asymmetries, open quotient, propagation of mucosal waves, movement of the upper and, in the closing phase, the lower margins of the vocal folds, etc. The technique is suitable for further processing and quantification of recorded vibration.

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.

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.

BELTING AND POP, NONCLASSICAL APPROACHES TO THE FEMALE MIDDLE VOICE - SOME PRELIMINARY CONSIDERATIONS

There is a commonly perceived difference in the sound produced in the approximate range D4-D5 by female singers in the western opera and concert tradition, on the one hand, and certain other styles, including rock, pop, folk, and some Broadway musicals, on the other. The term belting is sometimes used to refer to at least one approach to such nonclassical singing. In this study, based on spectrographic, electroglottographic, and sub- and supraglottal pressure measurements on representative voices of the operatic and nonclassical tradition, acoustic and laryngeal differences between the two traditions are described, and an objective, specific definition of belting is offered.

Anterior-Posterior and Medial Compression of the Supraglottis: Signs of Nonorganic Dysphonia or Normal Postures?

Two vocal tract postures commonly identified as hallmarks of nonorganic dysphonia are anterior-posterior and medial compression of the supraglottis. However, insufficient data exist to support their diagnostic utility. The purpose of this study was to compare these two postures in patients with nonorganic dysphonia and normal controls using interval data derived from quantitative measures of videostroboscopic images obtained with an oral endoscope. Retrospectively, 40 patients with nonorganic dysphonia and 40 normal controls were selected. Relative anterior-posterior compression (LO(AP)) was calculated as the laryngeal outlet (LO) (the view of the true vocal folds during phonation) normalized to the anterior-posterior dimension in pixels. Relative ventricular fold medial compression (LO(w)) was calculated as the laryngeal outlet normalized to the medial dimension in pixels. Results were as follows: (1) LO(AP) was significantly greater for the dysphonic group, (2) the range of LO(AP) values between the two groups overlapped considerably, (3) no significant difference was found between groups for LO(w), (4) the correlation between LO(AP) and LO(w) within each subject yielded r values of 0.71 and 0.67 for the nonorganic dysphonia and normal control groups, respectively. It is concluded that medial compression of the ventricular folds can be a normal laryngeal posture, and that although anterior-posterior compression is present in greater degree in dysphonics, it is sufficiently common in normals to question its utility as a diagnostic sign of phonatory dysfunction.

Consistency of the preoperative and intraoperative diagnosis of benign vocal fold lesions

The purpose of this retrospective study was to compare the preoperative and intraoperative diagnosis of benign vocal fold lesions for consistency. The diagnosis was made in 221 consecutive patients with benign vocal fold lesions for which a microlaryngoscopy was carried out in a general ENT-clinic. The preoperative diagnosis was obtained by both white halogen and stroboscopic light. The intraoperative diagnosis was obtained by direct microscopic visualization and palpation of the vocal folds. In 36% of the patients, the preoperative diagnosis was changed intraoperatively. In 31% of the patients, a lesion was missed at the preoperative examination and a lesion was diagnosed only during microlaryngoscopy. Bilateral lesions were found in 53% of the patients preoperatively, and in 82% of the patients intraoperatively. Specially intracordal lesions constituted a diagnostic pitfall. Because the preoperative and intraoperative diagnosis often differed, both the patients and the ENT-surgeon must keep an open mind about what may need to be done at surgery.

Measurement of Characteristic Leap Interval Between Chest and Falsetto Registers

A markedly smaller time constant distinguishes a chest-falsetto leap from the more usual execution of a sung interval by muscular adjustments in the length and tension of the vocal folds. The features of such a chest-falsetto leap are examined in detail with respect to F0, peak-to-peak amplitude of the vocal-fold contact area signal (EGG), and the closed quotient. A method is proposed to standardize and quantify this chest-falsetto leap in the characteristic leap interval (CLI), a measure of the separation between the natural registers in a given singing voice. The measure is applied to a varied group of experienced singers. Preliminary results include a suggested dimorphic pattern with respect to sex, with female voices exhibiting smaller CLIs and less individual diversity than male voices.

Resonance strategies for the belting style: Results of a single female subject study

This study explores resonance strategies used for the belting style and associated vocal fold vibratory patterns, for the vowels /e/, /a/, /i/, and /u/ on G4 and B4-flat. Acoustic spectra of belted vowels and their unoptimized, speech-like equivalents were compared. Vocal fold vibratory patterns were quantified using electroglottography. Results show that /a/ is inherently suitable for belting and requires no adjustment. For /e/, F2-H5 tuning was observed. For /i/, F1 was detuned from H1, enhancing also H2. For /u/, both F1 and F2 were raised to accomplish F2-H3 tuning. These results show that the loud, bright sound of the belting style is achieved by the implementation of resonance strategies that enhance higher harmonics. Electroglottography revealed that resonance strategies also result in raising the closed quotient (CQ) above 52%, an apparent threshold value for belting.

PHYSICAL DEFINITION OF THE FLAGEOLET REGISTER

The highest register of the female singing voice, often called the flageolet register (also called flute register, bell register, etc., as well as the misleading term whistle register), is broadly recognized by voice pedagogues, but not generally defined in terms that are adequate for objective description. This article presents a description of characteristic patterns of vocal fold movement and of vocal tract formants that are specific for the register. Measurements are made by electroglottograph, pharyngeally placed wide-band pressure transducers, and an external microphone in professional soprano subjects who are adept in using this register.

INTEGRATED AERODYNAMIC MEASUREMENTS

Summary The myoelastic-aerodynamic model of phonation implies that aerodynamic factors are crucial to the evaluation of voice function. Subglottal pressure and mean flow rate represent the vocal power source. If they can be related to the magnitude of the radiated sound power, they may provide an index of vocal efficiency. Methods of evaluating the aerodynamic characteristics associated with the ventilatory and laryngeal systems are critically discussed, and normative aerodynamic values for use in diagnosis and physiologic investigations are presented. Measurements having excellent time resolution of the glottal flow wave and of pressure changes in the vicinity of the larynx itself demonstrate the importance of study vocal tract acoustics.