An Analysis of Perceptible Overtones in the Voice
Don Lewis, William H. Lichte · The Journal of the Acoustical Society of America · 1938
Both oscillographic and phonographic recordings were made of a vocal sound in which five successively prominent partials were produced, in a few seconds, by a singer who meanwhile maintained the sound at a specified pitch level. Representative waves from the period of prominence of each partial were subjected to harmonic analysis, the results showing the physical bases for corresponding auditory experiences. Detailed investigation of the periods of transition from a given perceptibly prominent partial to the succeeding one revealed significant changes in energy distribution. For example, during the transition from the 4th to the 5th partial, there was found to be a 5 db decrease in the intensity level of the 4th, a 20 db increase in the level of the 5th, and a 10 db increase in the level of the 6th, with all other partials remaining essentially constant. The changes were gradual but rapid, and were apparently dependent upon resonance factors. The crucial importance of a given transition in attracting attention to a particular partial and, consequently, in shaping perception has been determined by psychological analysis.