Cup your hands behind each ear, like a Deer, to help you hear thing clearer and further away.
You might do this already when somebody says something to you and you don´t hear them very well. When you cup your hands behind your ears it gives to sound that would otherwise be passing by your head something to bounce off of and into your ears.
This is surprisingly effective and if you are listening out for something it can give you a real edge, increasing the distance that you can hear something from by quite a bit.
*I have read that it add about +/- 10 db to the perceived strength of the passing soundwave or in practical terms, give you 25-50 meters of extra range.
*that is a totally anecdotal story and I offer no evidence or warranty on it.