Louisa Traser

Vocal tract configurations in male alto register functions.

PURPOSE Professional male altos (countertenors) mostly use a register function, which is considered to be derived from falsetto. However, the sound produced differs in professional altos compared with the modal register or falsetto of untrained voices. The aim of this study was to analyze differences of the vocal tract shapes in male alto register functions. MATERIAL AND METHODS Dynamic real-time magnetic resonance imaging of eight frames per second was used to analyze the vocal tract profile in seven professional male altos who sang on the vowel /a/, an ascending and descending scale from G3 (196 Hz) to E4 (330 Hz). The scale included their register transition from modal register to stage (counter) falsetto and naïve falsetto. RESULTS Register transitions from modal register to stage falsetto were associated with increased lip opening, jaw retraction, elevation and back positioning of the tongue, pharynx narrowing, uvula elevation, drop of larynx height, and tilting of the larynx. Differences between stage and naïve falsetto were found mostly with regard to lip opening and pharynx width. CONCLUSIONS The differences between the vocal tract configurations might have an impact on the acoustic characteristics observed in professional male alto register functions.

Vocal fold vibrations at high soprano fundamental frequencies

Human voice production at very high fundamental frequencies is not yet understood in detail. It was hypothesized that these frequencies are produced by turbulences, vocal tract/vocal fold interactions, or vocal fold oscillations without closure. Hitherto it has been impossible to visually analyze the vocal mechanism due to technical limitations. Latest high-speed technology, which captures 20,000 frames/s, using transnasal endoscopy was applied. Up to 1568 Hz human vocal folds do exhibit oscillations with complete closure. Therefore, the recent results suggest that human voice production at very high F0s up to 1568 Hz is not caused by turbulence, but rather by airflow modulation from vocal fold oscillations.

Vocal Tract Configurations in Tenors' Passaggio in Different Vowel Conditions—A Real-Time Magnetic Resonance Imaging Study

OBJECTIVE The role of the vocal tract in registers is still unclear. Professional western classically trained tenors may reach their top pitch range by modifying vocal register functions. The aim of this study was to analyze the influence of vowel conditions on vocal tract configurations in different register functions. MATERIALS AND METHODS Dynamic real-time magnetic resonance imaging of 8 frames per second was used to analyze the vocal tract profile in four world-leading tenors (one oratorios/classical song, one light lyrical, one young dramatic, and one Heldentenor), who sang an ascending scale between C4 (261Hz) and A4 (440Hz) on the vowels /a, e, i, o, u, ae/. In one condition, they performed the scale to include their register transition from modal register to falsetto and, in another condition, sang with the continuation of stage voice across the passaggio. RESULTS The tenors show some vowel independent modifications with respect to registers. In contrast to falsetto, stage voice was associated with an increase of lip and jaw opening and a lower larynx position for most conditions. However, some articulators such as the pharynx width showed different progressions depending on the vowel conditions. In general, the dramatic voices have been found to show stronger articulatory changes than lyrical voices. CONCLUSIONS The vowel condition might, in part, affect vocal tract modifications due to register functions.

Acceleration of MRI of the vocal tract provides additional insight into articulator modifications

To accelerate dynamic imaging of the vocal tract during articulation.

Articulation and vocal tract acoustics at soprano subject's high fundamental frequencies

The role of the vocal tract for phonation at very high soprano fundamental frequencies (F0s) is not yet understood in detail. In this investigation, two experiments were carried out with a single professional high soprano subject. First, using two dimensional (2D) dynamic real-time magnetic resonance imaging (MRI) (24 fps) midsagittal and coronal vocal tract shapes were analyzed while the subject sang a scale from Bb5 (932 Hz) to G6 (1568 Hz). In a second experiment, volumetric vocal tract MRI data were recorded from sustained phonations (13 s) for the pitches C6 (1047 Hz) and G6 (1568 Hz). Formant frequencies were measured in physical models created by 3D printing, and calculated from area functions obtained from the 3D vocal tract shapes. The data showed that there were only minor modifications of the vocal tract shape. These changes involved a decrease of the piriform sinus as well as small changes of tongue position. Formant frequencies did not exhibit major differences between C6 and G6 for F1 and F3, respectively. Only F2 was slightly raised for G6. For G6, however, F2 is not excited by any voice source partial. Therefore, this investigation was not able to confirm that the analyzed professional soprano subject adjusted formants to voice source partials for the analyzed F0s.

Weight-Bearing MR Imaging as an Option in the Study of Gravitational Effects on the Vocal Tract of Untrained Subjects in Singing Phonation

Magnetic Resonance Imaging (MRI) of subjects in a supine position can be used to evaluate the configuration of the vocal tract during phonation. However, studies of speech phonation have shown that gravity can affect vocal tract shape and bias measurements. This is one of the reasons that MRI studies of singing phonation have used professionally trained singers as subjects, because they are generally considered to be less affected by the supine body position and environmental distractions. A study of untrained singers might not only contribute to the understanding of intuitive singing function and aid the evaluation of potential hazards for vocal health, but also provide insights into the effect of the supine position on singers in general. In the present study, an open configuration 0.25 T MRI system with a rotatable examination bed was used to study the effect of body position in 20 vocally untrained subjects. The subjects were asked to sing sustained tones in both supine and upright body positions on different pitches and in different register conditions. Morphometric measurements were taken from the acquired images of a sagittal slice depicting the vocal tract. The analysis concerning the vocal tract configuration in the two body positions revealed differences in 5 out of 10 measured articulatory parameters. In the upright position the jaw was less protruded, the uvula was elongated, the larynx more tilted and the tongue was positioned more to the front of the mouth than in the supine position. The findings presented are in agreement with several studies on gravitational effects in speech phonation, but contrast with the results of a previous study on professional singers of our group where only minor differences between upright and supine body posture were observed. The present study demonstrates that imaging of the vocal tract using weight-bearing MR imaging is a feasible tool for the study of sustained phonation in singing for vocally untrained subjects.

Morphometric Differences of Vocal Tract Articulators in Different Loudness Conditions in Singing

Introduction Dynamic MRI analysis of phonation has gathered interest in voice and speech physiology. However, there are limited data addressing the extent to which articulation is dependent on loudness. Material and Methods 12 professional singer subjects of different voice classifications were analysed concerning the vocal tract profiles recorded with dynamic real-time MRI with 25fps in different pitch and loudness conditions. The subjects were asked to sing ascending scales on the vowel /a/ in three loudness conditions (comfortable = mf, very soft = pp, very loud = ff, respectively). Furthermore, fundamental frequency and sound pressure level were analysed from the simultaneously recorded optical audio signal after noise cancellation. Results The data show articulatory differences with respect to changes of both pitch and loudness. Here, lip opening and pharynx width were increased. While the vertical larynx position was rising with pitch it was lower for greater loudness. Especially, the lip opening and pharynx width were more strongly correlated with the sound pressure level than with pitch. Conclusion For the vowel /a/ loudness has an effect on articulation during singing which should be considered when articulatory vocal tract data are interpreted.

A comparison of different methods to generate tooth surface models without applying ionizing radiation for digital 3-dimensional image fusion with magnetic resonance imaging-based data of the head and neck region

Objective The 3-dimensional display of the vocal tract and teeth is necessary in numerous clinical and scientific contexts. Due to the different tissue properties this can only be achieved by combining different imaging techniques. A comparison of methods to record the tooth surface to create combined models of the vocal tract and teeth without applying ionizing radiation is displayed in this study. Methods Four methods to record the tooth surface were compared concerning their clinical accuracy after combination with magnetic resonance imaging (MRI)–based vocal tract models. With 2 of the presented methods the information of the tooth surface was obtained from MRI data. With the other 2 methods, the tooth surface was captured using a digital and a conventional impression technique. Results Impression techniques received the best rating results. Conclusions The digital 3-dimensional image fusion of dental impression and MRI resulted in a virtual model of the vocal tract and teeth with a high clinical accuracy without applying ionizing radiation.

The influence of water resistance therapy on vocal fold vibration: a high-speed digital imaging study.

Abstract Purpose: This study investigated the influence of tube phonation into water on vocal fold vibration. Method: Eight participants were analyzed via high-speed digital imaging while phonating into a silicon tube with the free end submerged into water. Two test sequences were studied: (1) phonation pre, during, and post tube submerged 5 cm into water; and (2) phonation into tube submerged 5 cm, 10 cm, and 18 cm into water. Several glottal area parameters were calculated using phonovibrograms. Results: The results showed individual differences. However, certain trends were possible to identify based on similar results found for the majority of participants. Amplitude-to-length ratio, harmonic-to-noise ratio, and spectral flatness (derived from glottal area) decreased for all tube immersion depths, while glottal closing quotient increased for 10 cm immersion and contact quotient for 18 cm immersion. Closed quotient decreased during phonation into the tube at 5 cm depth, and jitter decreased during and after it. Conclusion: Results suggest that the depth of tube submersion appears to have an effect on phonation. Shallow immersion seems to promote smoother and more stable phonation, while deeper immersion may involve increased respiratory and glottal effort to compensate for the increased supraglottal resistance. This disparity, which is dependent upon the degree of flow resistance, should be considered when choosing treatment exercises for patients with various diagnoses, namely hyperfunctional or hypofunctional dysphonia.

Resonatory properties in professional tenors singing above the passaggio

Introduction: The question of formant tuning in male professional voices has been a matter of discussion for many years. Material and Methods: In this study four very successful Western classically ...