Just turn down the voice playback slider. When you start talking it makes all the game sounds quieter while you are transmitting or receiving voice. This lets you know when you have timed out on range.
As for the feedback, as far as I know most computers should have an option enabled by default that allow you to hear anything spoken into the mic but at a much lower volume. It's built in because humans use listen to their own voice when they talk to know if they are pronouncing something correctly. This is why deaf people sometimes mispronounce words, because they aren't able to hear this feedback.