The voice analyser was a device which was used circa 50000. It acted as a lie detector.
The bounty hunter Ahab carried a voice analyser. He used it to determine that Alistair Gryffen was lying about not knowing who K9 was, though he told the professor that he didn't need it. The analyser, along with its owner, was lost in space after he was forced through the STM. (TV: The Bounty Hunter)