Directional Microphone
From the Metal Gear Wiki
Directional Microphone a microphone that allows you to hear quiet noises coming from a particular direction. It is unusual for a sensor, in that it is under the weapons list instead of the items list in the survival viewer.
[edit] Usage
The Directional Mic is listed under weapons when it is equipped. The view is switched to first person view, with the Mic being held like a pistol. It can be aimed to amplify sound coming from that direction. When aimed at a character, their dialog appears as captions. However, the size of the captions depends on how well the mic is targeted at a character, so when eavesdropping on a conversation you have to make a compromise so you can hear both sides.
The item is available at Metal Gear Solid 2 and 3. In the Sons of Liberty, it can be found at the Plant Chapter at the B2 level of Shell 1 where the computers surround it (as well as a heavy patrol of guards around it). It is compulsory to be used in order to search for Richard Ames in the area. The Directional Mic is also seen used by Naked Snake in Metal Gear Solid 3 though does not have a important role in the game and is automatically in his inventory at the start of the mission.
