A device encountered in Castle Heterodyne, specifically, in the "medical lab" known as the Red Playroom. This particular lab was the favorite of Iago Heterodyne, who apparently loved the screaming of his experimental subjects so much that he installed an artificial scream generator for those occasions when the actual thing wasn't available.
The Scream Emulator is a versatile and flexible little gadget. Switches allow the operator to choose between opposites in "tuning" the screams -- "Agony" versus "Ecstasy," "Guilty" versus "Innocent," and so on. The volume control's two named settings are "Loud" and "Louder," which probably tells you everything you need to know about Iago Heterodyne.
Agatha and her party to the Red Playroom hoping to find supplies and equipment to stabilize the seriously wounded Tarvek, and the Scream Emulator is one of the gadgets they find there. Moloch is not so keen on the Scream Emulator. Tarvek's opinion is unrecorded.