You can acquire the mission "Torture Chairs" from Tannis immediately after finishing "Hidden Journals". You'll be sent to collect more ECHO recordings but these are much easier to find and they are all located in Sanctuary.
- XP: 2858
- Money: $765
- Gear: N/A
The first is in the dumpster near Marcus' gun shop. The next is in a pile of trash just outside the side door of Moxxi's club. Number three is out front of Scooter's under a pile of large tires near the very edge of Sanctuary. Fourth is found in the side observation room in Zed's room and the final recording is found at Claptrap's place on a book shelf to his left (your right).
When you've collected them all, return to Tannis for your reward.