Omni Directional Microphones: These microphones can respond to sound from all directions.
Directional Microphones: These microphones can respond to sound at a fixed angle. These are used in noise cancellation.
Eartell: It is important to convert omni directional to directional microphones in order to know the direction of the sound so that eartell can process the sound signal and distribute to the good ear.
Experiment: I purchased 4 funnels and then sliced the end so that the microphone perfectly fits inside the funnel, I tried the program (refer to my previous blog fro the program) to see if it is really working but it is still able to respond to the sound from all angles but it is little weak, I need to cover the funnel using a sound proof tape.