Das dreidimensionale Stimmfeld

Zusammenfassung

Die Erweiterung des Stimmfeldes durch eine dritte, den Phonationsprozeß beschreibende Variable hat sehr verschiedene Vor- und Nachteile. Aerodynamische Meßwerte stärken die Aussagekraft des Stimmfeldes als Repräsentant laryngealer Leistungsfähigkeit, andererseits kompliziert ihre Messung die Methode. Für die die Stimmqualität beschreibenden Variablen bilden die Grundfrequenz-Intensitätskurven zwar eindeutige Referenzwerte, jedoch ist die Stimmqualität längs dieser physiologischen Grenzkurven nicht repräsentativ für die normale Phonation. Für bzw. gegen in das Stimmfeld eingetragene EMG-Daten gelten ähnliche Argumente wie für die aerodynamischen Größen. In speziellen Fällen jedoch (Untersuchung der Sängerstimme oder Klärung wissenschaftlicher Fragestellungen) ist der Einbezug einer dritten Variablen sehr hilfreich

Summary

Extension of the voice field (voice profile) by a third variable which characterizes the phonation has various advantages as well as drawbacks. Since the voice field evaluates the laryngeal function, the use of aerodynamic variables improve the representation of the laryngeal efficiency in the voice field. On the other hand, the measurement of these variables complicates the method. When voice quality measures (presence of singing formant, sharpness) are used as the third dimension, the limits of the voice field are unique references for the measures. However, the voice quality at the physiologic limits is not representative of the voice as produced in singing or speaking. Measures which characterize the “hoarseness” of the voice yield important results with respect to the perturbation of the voice production (jitter, shimmer, additive noise). The perturbation measures evaluate the laryngeal function at defined points in the frequency - intensity area. However, in forte phonation, the natural perturbation is reduced, in piano phonation, the perturbation is increased, and the results cannot be interpreted in relation to the perturbation magnitude within the voice field. Besides, the measurement of perturbation requires digital signal processing. If EMG data are used for the voice field, as it is shown for the M. vocalis, the voice field reveals interesting relationships between acoustic and physiologic features. For instance, in the piano phonation, the EMG signal power is constant on a low level. In the forte phonation, in the chest register, the EMG signal power shows a medium level and a high level in the head register. In the falsetto, however, the EMG signal power is low. This method, however, is too expensive for phoniatric routine. The representation of the three-dimensional voice field requires more effort. An analytical evaluation of the three dimensional voice field appears very difficult. Nevertheless, for the examination of special cases or scientific questions, the inclusion of a third variable in the voice field may be very helpful.