Microphone Troubleshooting

They had given us a lecture theater that we did not use for taking lectures. I had sat there in my undergraduate days as a student. But the computer and audiovisual equipment had been installed much later, and I had not used it before. The computer and the projector worked OK. But the microphone was acting up. It would produce strange grunting noises every now and then, almost at a rate of once for every three words of mine. "Does it do this every time it is used?" I asked the students. "Yes" they said. I continued to teach them, and it continued to trouble me. They did not seem to mind much, probably because the subject matter was equally unwanted for most of them. I was getting disturbed because I preferred to hear only my voice while I taught. I glared at the speaker a couple of times, but that did not improve anything. Then I had an idea. I took out my handkerchief, and wrapped it over the mouthpiece of the microphone. The grunting stopped immediately. I grinned all over my face, and so did the students. "This made my day" I told them.