Toward a more informative voice range profile: the role of laryngeal vibratory mechanisms on vowels dynamic range.

PURPOSE: The impact that vowels have on the variation across voice range profiles (VRPs) is studied along with three factors: fundamental frequency, singer's gender, and laryngeal vibratory mechanism used to sing. MATERIALS AND METHODS: VRPs of 21 advanced singers were established by recording, in separate takes, vocal productions using laryngeal vibratory mechanisms M1 and M2 for /a/, /i/, and /o/. Recordings were focused on the range C3-C5, where most singers can sing in either M1 or M2. It allows to compare the singer's dynamics in M1 versus M2 while holding other variables constant. RESULTS: The vowel has an influence on the upper limit of singers' VRPs when they use M1 but not when they use M2, independently of the singer's gender and the fundamental frequency. DISCUSSION AND CONCLUSION: The laryngeal vibratory mechanisms allow one to explain the nonconsensual results observed in the literature about the influence of vowels on the VRP. A simulation shows that the different influence of vowels on the VRP partially results from the different open quotient values that can be observed in M1 and in M2.

Laryngeal vibratory mechanisms: the notion of vocal register revisited.

This study, focused on the laryngeal source level, introduces the concept of laryngeal vibratory mechanism. Human phonation is characterized by the use of four laryngeal mechanisms, labeled M0-M3, as evidenced by the electroglottographic (EGG) study of the transition phenomena between mechanisms with a population of men and women, trained and untrained singers. Macroscopic and local descriptions of the EGG signal are analyzed during the production of glissandos and held notes with different mechanisms. The transition from one mechanism to another of higher rank is characterized by a jump in frequency, a reduction of EGG amplitude, and a change in the shape of the derivative of the EGG (which may correspond to a reduction of the vibratory mass). These characteristics are used to identify a transition between two mechanisms, in complement with acoustic spectrographic analyses. The pitches of transitions between the two main mechanisms M1 and M2 and the range of the frequency-overlap region are described in detail. The notion of vocal register is revisited in the light of these concepts of laryngeal mechanism. The literature on vocal registers is reviewed, and it is shown that the confusion often cited with respect to this notion may be related to the heterogeneity of the approaches and methods used to describe the phenomena and to the multiplicity of descriptors. Therefore, the terminology of the registers is organized depending on their relation to the four laryngeal vibratory mechanisms.

Manuel Garcia Jr: a clear-sighted observer of human voice production.

Before Garcia, only a few notions of vocal production can be found in earlier singing treatises. In those days the authors wrote mainly upon the art of ornamentation and the rules of good language utterance. In the beginning of the 19th century, a radical change occurred with the development of scientific experiments. Several doctors or physicists drew up theories on human voice production, which were similar to those of sound production in woodwind instruments: flute, reed, or membranous lips. Yet, as the experiments on living human beings were impossible, the true nature of the vocal source remained under discussion. In addition, specific questions arose in regard to singing: Are the different registers produced by different vibrating sources or are they due to modifications of a single vibrating system? What are the reasons for a variation in loudness and in pitch, and how are the variations of voice timbre produced? Facing the contradictory opinions of the most famous scientists, Manuel Garcia Jr showed an astonishing insight as early as 1840, when he wrote his first 'Mémoire sur la voix humaine' presented to the Académie des Sciences de Paris. Being altogether an anatomist, a singer, and a great pedagogue, he could accurately observe the physiological phenomena of human voice in the right way. As the first user of the laryngoscope, he wrote a second paper presented at the Royal Society of London, in 1855, in which he confirmed his previous views. All along the different issues of his well-known singing method, we may see the lucidity and the improvements of Garcia's ideas. The only concession he made to the singers is related to the famous 'Fausset-tête' register, an unfortunate word that was bound to induce confusion later.

Glottal open quotient in singing: measurements and correlation with laryngeal mechanisms, vocal intensity, and fundamental frequency.

This article presents the results of glottal open-quotient measurements in the case of singing voice production. It explores the relationship between open quotient and laryngeal mechanisms, vocal intensity, and fundamental frequency. The audio and electroglottographic signals of 18 classically trained male and female singers were recorded and analyzed with regard to vocal intensity, fundamental frequency, and open quotient. Fundamental frequency and open quotient are derived from the differentiated electroglottographic signal, using the DECOM (DEgg Correlation-based Open quotient Measurement) method. As male and female phonation may differ in respect to vocal-fold vibratory properties, a distinction is made between two different glottal configurations, which are called laryngeal mechanisms: mechanism 1 (related to chest, modal, and male head register) and mechanism 2 (related to falsetto for male and head register for female). The results show that open quotient depends on the laryngeal mechanisms. It ranges from 0.3 to 0.8 in mechanism 1 and from 0.5 to 0.95 in mechanism 2. The open quotient is strongly related to vocal intensity in mechanism 1 and to fundamental frequency in mechanism 2.

[Laryngeal registers as shown in the voice range profile]. / Phonétogramme par registre laryngé.

Voice range profile (VRP) is a well-known vocal test. Usually, it consists of a single diagram based on the whole voice range. When practised separately in each individual laryngeal mechanism, VRP may offer much information on both the relative development of the different mechanisms used by the subject and the extension of the common area between two consecutive mechanisms. We present the results obtained from 42 subjects of both sexes who have different singing technique levels: professional singers, student and amateur singers, as well as subjects without any experience in singing. For each mechanism, the global VRP area and the dynamic range were computed. Results are discussed in relation to sex category and vocal training of subjects. Exploring systematically VRP for each mechanism gives new and valuable information on register managing in singing practice.

On the use of the derivative of electroglottographic signals for characterization of nonpathological phonation.

Electroglottography is a common method for providing noninvasive measurements of glottal activity. The derivative of the electroglottographic signal, however, has not attracted much attention, although it yields reliable indicators of glottal closing instants. The purpose of this paper is to provide a guide to the usefulness of this signal. The main features that are to be found in this signal are presented on the basis of an extensive analysis of a database of items sung by 18 trained singers. Glottal opening and closing instants are related to peaks in the signal; the latter can be used to measure glottal parameters such as fundamental frequency and open quotient. In some cases, peaks are doubled or imprecise, which points to special (but by no means uncommon) glottal configurations. A correlation-based algorithm for the automatic measurement of fundamental frequency and open quotient using the derivative of electroglottographic signals is proposed. It is compared to three other electroglottographic-based methods with regard to the measurement of open quotient in inverse-filtered derived glottal flow. It is shown that agreement with the glottal-flow measurements is much better than most threshold-based measurements in the case of sustained sounds.

Just noticeable differences of open quotient and asymmetry coefficient in singing voice.

This study aims to explore the perceptual relevance of the variations of glottal flow parameters and to what extent a small variation can be detected. Just Noticeable Differences (JNDs) have been measured for three values of open quotient (0.4, 0.6, and 0.8) and two values of asymmetry coefficient (2/3 and 0.8), and the effect of changes of vowel, pitch, vibrato, and amplitude parameters has been tested. Two main groups of subjects have been analyzed: a group of 20 untrained subjects and a group of 10 trained subjects. The results show that the JND for open quotient is highly dependent on the target value: an increase of the JND is noticed when the open quotient target value is increased. The relative JND is constant: deltaOq/Oq = 14% for the untrained and 10% for the trained. In the same way, the JND for asymmetry coefficient is also slightly dependent on the target value--an increase of the asymmetry coefficient value leads to a decrease of the JND. The results show that there is no effect from the selected vowel or frequency (two values have been tested), but that the addition of a vibrato has a small effect on the JND of open quotient. The choice of an amplitude parameter also has a great effect on the JND of open quotient.