Stealth Enhancer

 "A cranial implant with a series of hair-thin dermal sensors (typically implanted along the crown of the skull), the Stealth Enhancer ties in to the existing vision augmentations and provides a direct feedback to the level of ambient sound generated by the user. The implants central processing unit can also perform instant situation-based analysis of targets indentified via line-of-sight, and is vapable of predicting he vision cones of these targets with great accuracy, even after loss of direct observation"

-taken from in-game description

One of the augmentations that the player has to unlock. At the cost of 2 praxis points, it can seem a pretty low-priority augmentation as opposed to the Icarus or other augmentations. Especially at the first level, which only tracks how much sound you are making (which is pretty useless since most stealth players will move either crouched or from cover to cover). The real charm of this aug shows later down the tree with the vision cones (reminicent of MGS series), the Mark & Track system, and the Last Known Position system (both latter reminicent of SC: Conviction).