Any sound whether it is song or speech has two basic parameters. Men have a larger larynx and their vocal cords are longer. However, every larynx has the capacity to produce a range of pitches. Asha Bhosle can go from one pitch to another quite effortlessly because she has a trained singing voice. Maybe not to her degree of control, but all of us are also capable of producing more pitch levels than we do.
Every larynx has an optimal pitch level depending on individual factors.
If this optimal pitch is identified and used, the resultant voice will have a pleasant quality and the speaker will be able to produce it with a minimal of effort. The best voice is one which is produced effortlessly Vocal Projection To enable her to be heard even by students on the last benches in the classroom, Usha will need to practice voice projection which is one of the techniques taught to stage actors. Considering that this problem affects many teachers in many schools and colleges, it might not really be a bad idea for the school authorities to conduct short courses for their teachers to promote better speech habits and thus prevent or minimize the incidence of voice-loss amongst their teachers.