Audio logs are scattered throughout all five chapters of Bendy and the Ink Machine. These recordings provide invaluable backstory, character development, and insights into the events that led to the studio's downfall. Listening to them is crucial for understanding the full narrative.
Each audio log is typically found on a desk, shelf, or other prominent surface. When you approach one, an interaction prompt will appear. Once activated, the recording will play, often featuring the voices of Joey Drew, Sammy Lawrence, Susie Campbell, Wally Franks, and other studio employees. There are over 30 audio logs in total. While not strictly a 'side quest', collecting all of them is a significant optional activity that enriches the game's lore. Many achievements are tied to finding specific sets of logs or all of them. Always explore thoroughly, as some are cleverly hidden in less obvious areas. They often provide context for the puzzles you're solving or the enemies you're encountering.