A good starting point might be to read the work of Deborah Tannen (see citation below). She is a linguist who has studied the way speech habits and silence affect power in business meetings. In particular, she investigates the gendering of power, showing that men actually talk more than women, interrupt more than women do, and interrupt women more than men in business meetings. She shows that this silencing actually affects the power balance in meetings and in whom is given credit for ideas. Speech coaches train women to participate more assertively in meetings so that their voices will be heard, empowering them.
For your essay, you could talk about specific case studies with Tannen's work in terms of voice and power.