Ow can I comprehensively set up a Bluetooth mic on the IPAD 2 in such a way that The Dragon Dictate app will recognise it and will ignore any extraneous sound that may come in from the internal mic .

I have already successfully paired the mic using Bluetooth in settings but how do I get Dragon to recognise it (and only it)

I am stumped .... And not generally used to being stumped !!!!! ( I bet it's as simple as pie and I am just being daft !!!!)