Even the most expensive and sensitive microphones pick up what is closest to them most clearly.  Although the shape and type of microphone makes a difference, for the most part the sounds in between what you want to hear and the microphone (like noises in the environment) are going to be recorded along with the audio you are trying to capture.  For example: if you are in the middle of the audience in a large theater and you hold a up a microphone to record the sound of the actors on stage but the person sitting in right front of you is talking, what you will get on your recording is the talking person near you loud and clear with the actors on stage barely audible in the background.  So a good rule of thumb is – get the microphone as close as possible to what you want to hear most clearly.