When we think about the restorative properties of nature, we usually think of presences: the presence of greenery, the presence of birdsongs, the presence of physical exertion, etc. What may be surprising is the absences within nature. One of the most notable is the absence of noise. Constant loud noise is rare in non-human nature; there may be short periods of a few days or weeks where large breeding colonies of birds make a ton of noise for much of the day and/or night, but these are the exception rather than the rule. And even in these mass gatherings, the animals are generally able to get away from the commotion to hunt for food for their young.
What many people experience, particularly in crowded urban areas, is an unnatural level of constant noise during most or all of a typical twenty-four hour period. Our brains are only wired to filter out so much noise for so long before fatigue sets in; we may think that we’re dealing with it alright because we don’t often notice it consciously. This is a case of self-defense.