The microphone would be really useful and inter...

The microphone would be really useful and interesting, but I think that it has been kept off since Phoenix landed because there may be a problem with its circuitry that could possibly cause a bigger short circuit that might endanger the entire lander.

That's why it has not yet been used. I've heard that towards the very end of the mission, the managers might switch the mike on when the risk is not as great. Here's hoping!