Why Musicians place their lips close to the Microphone when they sing

Hi, I need an essay written for my Sound Recording course at Uni. It's a Research Assignment. The topic i have chosen is "Why Musicians put their lips so close to the microphone when they sing". It can be a discussion rather than an essay. Create a premise and conclusion. Please include diagrams and examples. I have done some research and gathered information about this topic, which will be attached for you to use.