Hearing is a Sense allowing Perception of Sound. Targets which enter through this sense are modified to be Hearing-Based.
B358 assigns special modifiers to the roll based on distance which differ from the standard three sytems of range-based penalties (-1/yard for spells, the speed/range table for guns/sight, the long-distance modifiers for info spells)
Like all sights, use of Hearing involves two rolls: a sense roll (which can be increased by Acute Senses like Acute Hearing, plus Discriminatory Hearnig or decreased by Bad Hearing) to see if you detect something and if successful, an IQ roll to interpret the detected things.
Danger Sense can kick in when all other sense rolls fail.
B394 has rules on how this can allow a parry or dodge against an unseen foe.
None appears to be needed each time you want to dodge an unseen attacker but Hearing might be involved in knowing one is under attack in the first place if there's no other indicator (like suffering an injury)