A person recently asked me what I meant by the term business system.. I thought others might like to know a definition that works for me. A system is a procedure, process, method, or course of action designed to achieve a specific result.
The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz. Thus, the fundamental frequency of most speech falls below the bottom of the voice frequency band as defined above.
It's the same now as it has been all through history: (1) the most typical female voice is the mezzo soprano; and (2) most pop songs are written for a voice register of less than an octave. If you're a real soprano, you can sing just about anything. You just have to select the correct key for YOUR voice.