Learning to use sound was so important to my enjoyment and mastery of the game that I would fault the developers Creative Assembly for not making it more obvious during the training levels. To be honest I would fault training in the game in general. This is an unusual style of game that requires players to rethink their normal playing assumptions in order to survive. Like many others I struggled with the first few levels of the game until I eventually figured out how to play. To be honest I almost gave up out of frustration. It is not just that the game doesn't give you direction. Very often gives you misleading direction. Here are some glaring examples:
1) When faced with an unstoppable alien monster your natural instinct is to run and hide. The game reinforces this by liberally sprinkling every level with cabinets marked "Click to Hide Here". While these can sometimes be useful they are usually death traps and running to the nearest one to hide in is a death sentence. They make a racket getting in and out and the monster can hear you breathing inside. Worse still you have no where to run if the monster does come for you.
2) The motion tracker is surely the greatest con-job of all. As a novice player I clutched it deperately trying to figure out where the monster was, not realising that the beeping of the device was actually giving away my position. Staring at the motion tracker distracts you from the much better information that be be obtained simply by listening and looking around. In my opinion the motion tracker should spend most of its time in your pocket only pulled out occasionally when you know you are safe in order to get an idea of where to go next. It still serves some use in your pocket because it gives an audible warning if an enemy appears nearby.
3) Directional sounds are an absolutely essential tool for tracking enemies in the game but the developers delight in adding plenty of misleading bumps, creaks and other scary noises. This certainly adds to the scary atmosphere but it does confuse novice players. You start jumping at every bump and it takes a while before you learn to pick out the important sounds from the background noise.