Interesting idea. I think the biggest challenge would be to filter out noise (i.e wind blowing on the microphone). But in a limited domain such as this you can

Interesting idea. I think the biggest challenge would be to filter out noise (i.e wind blowing on the microphone). But in a limited domain such as this you can do aggressive filtering and get fairly good results in very harsh environments. Really cool idea. Now I have a strange urge to break out the ArduCopter.