system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How does the human ear discern between a quiet noise and a distant noise?
gpt
A quiet noise from a nearby source will have more high frequency content than the same noise made much louder from far away. This is because air absorbs high frequency sound energy over distance but not low frequency to the same extent (think about how a plane sounds low and rumbly from far away, but when you are close, it sounds like all of the frequencies).

Additionally, nearby sounds will create stronger reflections off of surfaces close to you, creating a more full sound compared to distant sounds which will most likely consist of just one apparent location, or the reflections will be recognized as an echo, another indication that the sound is a large distance away.

If you are not near any other objects, the first effect will be the predominant way your ear/brain make the distinction.