The sounds you hear while walking rarely come from one source, footsteps, distant traffic, wind, the odd bird. Researchers call this kind of mixed, low-intensity soundscape “soft fascination.”
Soft fascination means the mind is engaged without locking onto anything specific, but it's not fully idle either. That in-between state turns out to be exactly where creative thinking and mental recovery happen most.
You can't fully recreate that feeling indoors, but building a similarly layered, low-intensity soundscape at home opens up a comparable space for the mind to unwind.