Messa di voce: an investigation of the symmetry of crescendo and decrescendo in a singing exercise.

A classical vocal exercise called "messa di voce" (Italian for "placing the voice") was used to study the symmetry of intensity increase and decrease in six trained singers. Ideally, the exercise is performed as a symmetric triangle, a linear increase in loudness, followed by a linear decrease. Given that some physiologic variables, like lung volume, undergo unidirectional change rather than a symmetric reversal, there is reason to believe that symmetries may not exist. It was found that highly trained singers who use large SPL ranges tend to abbreviate the decrescendo phase in comparison with the crescendo phase. In a few other cases, a plateau in SPL is reached, but an increase in loudness may still be perceived on the basis of a stronger vibrato or changes in timbre.