The voice is probably the most widespread musical instrument. The vocal folds are set into
            vibration by an overpressure of air in the lungs, the subglottal pressure being the main tool for
            varying vocal loudness. The sound is gerenated by the vocal fold vibrations which chop the
            airstream from the lungs into a pulsating airflow. This signal is filtered by the vocal tract resonator.
            Breathing is obviously of relevance to voice production.  
             A desirable voice quality and vocal health are important goals both in singing teachers’ studios and
            in voice clinics, and according to experience, breathing strategy is highly relevant to achieve these
            goals. In particular, many voice disorders, especially in women, are functional, i.e., caused by
            inappropriate phonatory habits. Voice therapy is often an appropriate treatment where one
            important component is to give the patient an adequate breathing technique. This leads to the overall
            topic of this project:  

                        RELATIONSHIPS BETWEEN BREATHING AND PHONATION 

             Subglottal pressure is regulated by both active and passive forces. The active forces are supplied
            by the respiratory muscles. The passive forces are produced by gravity and elasticity. The elasticity
            forces are strongly dependent on lung volume, high lung volumes producing high positive pressures
            and low lung volumes producing negative pressures. Therefore, in untrained voices, vocal sounds
            tend to be louder when produced at high than at low lung volumes. In trained voices such effects are
            compensated for by activation of respiratory muscles.  
            The project, originally funded by Axel och Margaret Ax:son Johnsons Stiftelse and by Sven och
            Dagmar Saléns Stiftelse, was initiated in january 1995. It has been carried out by two doctoral
            students, Monica Thomasson, singing teacher, and Jenny Iwarsson, speech therapist who finished
            her doctoral dissertation January 2001. Johan Sundberg has served as their supervisor and the
            principal investigator.  
            Several effects of of lung volume on the glottal voice source have been revealed in healthy, vocally
            untrained subjects. The results show that with decreasing lung volume, glottal adduction decreases
            and the larynx tends to rise. Both these effects, generally assumed to be relevant to vocal health,
            seem associated with a mechanical force, the tracheal pull. This force, which decreases with lung
            volume, pulls the larynx downward and counteracts glottal adduction.  
            Lung volumes have been measured in professional classical singing. It was found that the singers
            typically initiated their phrases at clearly higher lung volumes than untrained speakers. This means
            that singers need to deal with much greater elasticity forces than speakers.  Also, their rib cage and,
            in some singers, also the abdominal wall movements were accurately replicated when the singers
            repeated the same phrase.  
            The results demonstrate how the voice can be influenced in various ways by lung volume and
            breathing technique. A scientific description of these influences will provide a solid platform for the
            teaching of singing and for clinical voice therapy.  
            In the experiments respiratory inductive plethysmography (Respitrace) has been used for measuring
            lung volume and breathing movements. The voice source is analysed by inverse filtering of the oral
            flow captured by the flow mask.  

             Publications 
            Iwarsson J. Breathing and phonation, doctoral dissertation, the Karolinska Institutet January 2001. 
            Iwarsson J, Thomasson M & Sundberg J. Lung Volume and Phonation. A methodological study,
            Logopedics, Phoniatrics, Vocology 21 (1996) 13-20.  
            Iwarsson J, Thomasson M & Sundberg J. Effects of Lung Volume on the Glottal Voice Source,
            Journal of Voice 12 (1998) 424-33.  
            Iwarsson J & Sundberg J. Effects of Lung Volume on Vertical Larynx Position during Phonation,
            Journal of Voice 12 (1998) 159-65.  
            Thomasson M & J Sundberg. Lung volume levels in professional classical singing, Logopedics
            Phoniatrics Vocology 22 (1997) 61-70. 
            Thomasson M & J Sundberg. Consistency of phonatory breathing patterns in professional operatic
            singers, Journal of Voice 13 (1999) 529-41. 
            Thomasson M & J Sundberg. Consistency of inhalatory breathing patterns in professional singers,
            Journal of Voice 15 (2001) 373-83.