Loudness is controlled by the amount of air exhaled and not by using greater force at the laryngeal level. So one of the first things Usha should do is to learn to focus her energy towards developing greater 'lung power' rather than tightening her neck muscles. Actually, tense muscles interfere with loudness rather than help it. Speaking with continually tense muscles has undesirable long term repercussions too. 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.