Voicelocks

"Alright, alright, check this out." Tarvo gestured at the open vault door. Inset into the edge of the door and the vault frame was a curious clockwork mechanism. A clay disc set in the frame had a curious circular pattern on it, coming from the edge of the disc towards the center, then back out on the other side, curved and sinuous. Tarvo pointed at the area of the door edge opposite the disc, with a circular depression and a needle.
"See this? Newest technology available." He pulled a lever on the vault door and a gap opened; he rolled in a new disc and it clicked into place. "A scale in the door checks that the disc is the appropriate size and weight. The gears won't turn if there isn't enough weight, and the discs won't form a seal if they're not the right size." He closed the door, and as soon as the vault shut, the sound of grinding gears could be heard. Tarvo tried the door lever. "Locked, of course. One way cam automatically locks the door when closed."
Phanae folded her arms. "Okay, so whats the big deal?"
"Watch." On the face of the vault door was a curious circular area with a membrane stretched over it; Tarvo moved closely and positioned his face immediately before it. He pulled another lever on the door and began to sing, with the sound of more grinding gears serving as a backdrop.
"Unlock! The unlocking soooong! Unlooooock!"
Phanae stifled a giggle as Tarvo pushed the lever back into place. She could hear water flowing somewhere in the mechanism. After ten seconds, Tarvo tried the door, and it opened, with the sound of a jug of water being dumped on the floor. Phanae stepped over the puddle.
"Ingenious enough, I guess, but what was wrong with a normal key vault? If you have to record the pattern of your voice, what happens if you get a cold?"
Tarvo shrugged. "Don't get sick, I guess."

Utility

Voicelocks use the fact that clay disc needle patterns can be used to route fluid. Within the mechanism of a Voicelock, an initial voice pattern is recorded with the owner of the lock saying (or singing) something into a resonating membrane attached to a needle, positioned over a rotating clay disc. The initial etching pattern is then placed into the Voicelock permanently. When the Voicelock is subsequently used, anyone attempting to open the lock must insert a fresh clay disc into a porthole on the outside of the door, then pull a lever an re-record a vocal pattern that precisely matches the initial pattern. When they do so, should the discs match to within a certain level of tolerance, water will flow through the channel created by the matched etchings. After a certain time, if enough water is deposited onto a scale on the other side of the discs, the vault lock will disengage and the door will open. If the patterns on the discs do not match, not enough water will flow, and the lock will remain engaged.
The idea of a Voicelock was to create a high security vault that could only be entered by the person who initially recorded their own voice pattern on the clay disc inset when the Voicelock was installed. Laudable in ideal, but the frequent false negatives made the lock finicky and unpleasant to use in business. One owner of a Voicelock got tired of having to constantly re-record his voice and simply left his first successful voice pattern etching in the Voicelock permanently, rendering the lock always open and defeating the purpose.

Manufacturing

Although complex in design, the parts for a Voicelock are in widespread manufacture across Etoile, and a skilled technical engineer could construct one in roughly a week on-site.

Parent Technologies

• Power

Access & Availability

A few Voicelocks were sold, but the technology was a commercial failure. One is held at the Etoilean Museum as an exhibit.

Complexity

Voicelocks are reliant on Power and are finicky, requiring regular maintenance to keep a charged flywheel active and refills on their water reservoir. The mechanism is highly complex and prone to regular breakdowns.

Discovery

The curiosity of recording a pattern on clay with a needle attached to a membrane found its first commercial use in 722, when Voicelocks were shown off at the Etoilean Inventor's Exhibition that year. It was built more as a technological example than as a working lock, in an attempt to find some sort of use for recorded needle patterns.