Okay, so after listening to the audio file on repeat for about an hour and experimenting with various items, my sister and I have determined several things.
1. There was a match lit, then a kerosene lamp (there’s a specific sound to those old lamps)
2. There is some sort of machinery in the background, but we couldn’t make out much. Sounds like it has some sort of fan?
3. The writing sound was made by a fountain pen on old-style paper writing on a wooden surface with uneven grain and a worn finish. (Seriously, you have no idea how many combinations of writing utensils and surfaces we tested this with to get a perfect match.)
4. Judging by the sound of the footsteps, the person was wearing dress shoes and walking on a stone or possibly tile floor, though stone is more likely. (We borrowed some of dad’s shoes and made use of the vaguely chaotic design of our house.)
Also, apologies to @reverseblackholeofwords and @lum1natrix. This is what happens when you tell your sister she can tag people on the post and she has no idea what that means. Also @alcordraws and @markired, we figured you guys might like this, too. (And if not, that’s totally cool, too.)