Sound pressure level and spectral balance linearity and symmetry in the messa di voce of female classical singers.

The messa di voce, in its pure form a crescendo and decrescendo on one note, has been revered for centuries in classical singing, but the pedagogical assumptions of linearity and symmetry have received little critical assessment, especially across a wide fundamental frequency (F0) range. Five trained female classical singers performed a total of 318 messe di voce across their musical F0 range to identify its acoustical characteristics and the influence of F0. Sound pressure level (SPL) range was generally greater during crescendo at higher F0's and during decrescendo at lower FO's. Change in SPL during the messa di voce was predominantly nonlinear, and the shape of the SPL traces differed greatly between crescendo and decrescendo. Nonlinearity in SPL change was not related to SPL range but did show a F0 influence in decrescendo. Change in spectral balance (0-2 vs. 2-4 kHz) with respect to SPL change showed markedly more symmetry than linearity, so that changes in the mode of phonation during the messa di voce were dependent upon SPL regardless of whether the singer was in crescendo or decrescendo. Perceptual and physiological implications are discussed.