When playing Diablo II it is possible to open various containers (treasure chests, crates, bags etc), which all make a sound upon opening. Containers can be empty, contain beneficial items, or trigger traps. Though trapped containers appear randomly, the sound they make when opened is different to that of standard containers. Since the traps themselves take a few seconds to trigger it’s possible to reach a safe distance thereby avoiding injury. Of course this is only possible if you are being attentive.
The differences between the noise for a ‘Safe’ and a ‘Trapped’ container is not substantial but it is noticeable if you are listening for it. If you haven’t been paying attention, or haven’t learnt the correlation between the different sound and a trap, then you could [come to] believe all containers make the same noise, and suffer for it.
Through a single simple mechanic Diablo II encourages players to pay attention to their environment.