Directional stimuli are environmental stimuli, particularly light and sound, that the direction of which it comes and the direction of the response to the stimulus are of upmost importance. Non-directional stimuli are those where receptors do not detect the direction from which they come. Chemical stimuli are usually not directional.

No. 3D soundcards are omni directional

Omni-directional microphones are meant to pick up sound from any direction at any time. Unidirectional microphones pick up sound from only one direction.

Sound cancelling headphones work in two ways. Firstly, they are created from materials that do not absorb sound easily. Secondly, quality speakers are used in order to deliver sound in a directional manner.

It may be you have a directional mic instead of an omnidirectional mic. A directional mic will only pick up the sound it is pointing at. BTW, microphones do not have a volume control to turn up, they have a gain control.