During battle a Haemonculus tortures captured slaves and traps their screams in special voiceboxes. These cries of agony are filtered through complex projectors to create a wave of terrifying sonic energy around the vehicle, which can scatter enemy units. A vehicle with a Torture Amp is able to Tank Shock, even though it is not a tank.
Errata — Chapter Approved: Codex: Dark Eldar Q&A (v2.0): A Raider with both a Torture Amp and Slave Snares cannot Tank Shock a unit and also hit it with Slave Snares in the same turn — the two are mutually exclusive: Tank Shocking represents the Raider dropping to just above ground level and driving through the unit like a normal tank, while Slave Snares represent it flying over the unit instead.