Coordination between posture and phonation in vocal effort behavior

Abstract

*EVA is a device which, attached to a computer, allows for recording and assessing simultaneously several vocal and word parameters, such as: fundamental frequency, intensity (sound pressure level), instability levels (jitter, shimmer, variation coefficient), spectral analysis, air volumes in breathing and speech, glottal resistance development. Available at: http://www.sqlab.fr/ (SQLab-LPL, Aix-en-Provence, France). **SMART is a software for biomechanical analysis of movement, and is capable of integrating movement data synchronized with information derived from analogical devices, such as: strength platforms, electromyography (EMG) or other devices. It consists of infrared cameras, with 120 Hz frequency acquisition and a 768x576 pixels resolution, retromarker reflex device. The study of Lagier et al. (2010) approaches a very important aspect of vocal production, which concerns the reciprocity of implications between postural adjustments and phonation. However, in spite of the importance of this issue, the authors reported in their literature review that there are few studies about this matter, even though it is widely approached in the clinical practice of speech therapy. The authors based themselves on the assumption that the movement that is associated to vocal effort is structured, and involves the entire body. Thus, the head and other body parts have specific patterns of movement during phonation. Based on this premise, Lagier and collaborators conducted a study which had the purpose of determining whether body movement is a collateral effect of vocal effort or a part of effort behaviors in communication. For this purpose, the authors evaluated, simultaneously, the voice and posture of 20 speaking women, with an average of 26 years of age (interval: 20-43 years) with no history of laryngeal cancer, and without auditory disorders or postural issues. The subjects engaged in communication with a listener, aiming to be understood. They were asked to repeat 16 times, randomly, a series of numbers, short and informative words, with the purpose of increasing vocal effort in three different conditions:-weak vocal effort (WVEC): subject and listener placed 4 meters (m) apart from each other, in a calm room with inside noise level varying in between 44 and 48 dB;-moderate vocal effort (MVEC): same conditions as above, but with speaker and listener placed 10 m apart;-high vocal effort (HVEC): the distance between subject and listener was 10 m, and both wore earphones playing a soundtrack composed by mixed sounds (reference: Phonak Party Night Noise), at an average of 90 dB SPL, combining reduced auditory feedback and Lombard effect. …