Hello, thank you for your feedback! We are delighted to hear you've been enjoying our demo so far :) We're still making adjustments to in-game volumes, so in the meantime we recommend lowering the BGS volume in the options menu to better listen out for other environmental sounds.
If you've read the writing displayed above the cabinet in the same room as the small key, notice anything unusual about how some letters are colored? What significance could they have in relation to the clues gathered? We'll be glad to assist you with more hints, so feel free to ask further if you'd like them!
You're so close to solving this puzzle, the last clue might just be under your feet ;)