This problem constitutes a part of the experimental work in the psychology of music whose ultimate aim is to discover the objective criteria for artistic performance in vocal and instrumental music. Metfessel has shown, by making graphic representations of the voices of several famous singers, that artistic vocal production almost invariably contains a vibrato, which may be defined as a frequency-intensity fluctuation occurring in a regular periodicity usually not more than eight and one-half times or less than five and one-half times per second, and seldom covering a range of more than one full tone.
Proceedings of the Iowa Academy of Science
©1928 Iowa Academy of Science, Inc.
Tiffin, J. H.
"An Experimental Study of Variations in Breath Pressure in the Vocal Vibrato,"
Proceedings of the Iowa Academy of Science, 35(1), 297-298.
Available at: https://scholarworks.uni.edu/pias/vol35/iss1/66