The purpose of the study was concerned with specific elements of the portion of the female voice commonly referred to as whistle or flute register. Three elements of vocal production were chosen for which past research has demonstrated relationships to source function. These elements included spectral characteristics, airflow rates, and perceptual identification. The research compared what the singer-subjects perceived as being whistle register phonations with that which they perceived as being head register phonations. A comparative technique was utilized where pitch, intensity and phonemic category were held relatively constant, register, therefore, being the only variable. Spectral characteristics and airflow rates of the two subject-determined registers were compared. In addition, an attempt was made to determine if the whistle register could be perceptually differentiated on the basis of voice quality,