Well, the problem isn't what you're saying, it's that if it picks up any sound at all from your speakers and plays it back to you, that sound will be picked up by the microphone again and again and again, causing it to be painful for anybody who has to listen to your mic. The closer to you the better, that also means it picks up less environmental noise, and also, turn down your speakers if you do get some reverb, it will cause your mic to pick up less.