Virta building, auditorium 109, address: Åkerlundinkatu 5
Doctoral defence of Licenciado en Fonoaudiologia Marco Guzman
The field of science of the dissertation is Speech Technique and Vocology.
The opponent is Professor Mieke Moerman (Ghent University, Belgium). Professor Anne-Maria Laukkanen acts as the custos.
The language of the dissertation defence is English.
An investigation of the effects of vocal exercises that apply a semi-occlusion to the vocal tract
The methods that are used in voice training and therapy can be classified into those that promote general vocal health, those that base on psychological factors, and symptomatic and physiological methods.
The last mentioned have been investigated most up to now. They apply a semi-occlusion to the vocal tract. Such exercises include for instance voiced fricative (e.g. v, z), nasals (e.g. m), close vowels (like y) or lip and tongue trills (r), and phonation into different tubes. The other end of the tube can be held in the air or sunk into water. All these exercises slow down the airflow from the vocal tract.
This dissertation investigated what happens in the vocal organ during these exercises and whether the effect remains for some time after the exercise. The study considered the vocal tract, vocal fold vibration, airpressure during phonation and the acoustic structure of the voice as well as auditory perception of the voice. Methods included e.g. computerized tomography and high-speed filming. Participants (in total 75) were both normal voiced subjects either with or without voice training and voice patients suffering from different types of voice disorders.
According to the results, semi-occlusion exercises affect simultaneously the three components of voice production (airpressure, vocal fold vibration and the size and shape of the vocal tract). The changes observed can be beneficial both for voice training and for voice therapy. These changes promote a more effective (louder, better projecting) and economic (less loading, more endurant) voice production. Exercises that offer a stronger airflow resistance (like phonation into a narrow straw or into a tube sunk e.g. 10 cm deep in water) result in larger changes, and thus can be regarded as more effective. On the other hand, they also intensify vocal fold vibration, which makes them more suited for training asthenic type of voice production (e.g. presbyphonia or vocal fold pareses). Exercises that offer less airflow resistance (e.g. phonation into a tube, sunk only a couple of centimeters below water surface) are more suited for relaxing effortful, pressed phonation.
The dissertation is published in the publication series of Acta Universitatis Tamperensis; 2265, Tampere University Press, Tampere 2017. The dissertation is also published in the e-series Acta Electronica Universitatis Tamperensis; 1766, Tampere University Press 2017.