I recall projects that did something like this. Besides museums and historic neighborhoods, one memorable application was at a graveyard. Reenactors read letters and diary entries written by the deceased. The closer you were to the writer's tombstone, the louder their audio. From far away all you heard was a combination of barely audible voices. I believe the relevant terms are "audio walks" or "phonoscapes".

I have created something similar for a museum. I placed bluetooth beacons behind the exhibits, and when visitors approached them the app automatically switched to the "page" for this exhibit. The app was able to display texts, videos, images and audio files.