A skull simulator tests and calibrates bone-conduction vibrators under realistic operating conditions. In known skull simulators, the front wall of the casing—and/or exposed parts of the suspension—have one or more planar surfaces on the front, and these planar surfaces are thus oriented towards the bone-conduction vibrator when it is mounted on the skull simulator. Such planar surfaces may reflect airborne sound from the vibrator housing or may emit sounds themselves when vibrating, and the reflected or emitted sound contributes to resonances are not present when the bone-conduction vibrator is mounted on a human head. In the current design all exposed parts on the front located outside a coupling surface for connecting the bone-conduction vibrator do not have planar surfaces perpendicular to the main oscillation axis or that otherwise, such planar surfaces comprising an acoustic foam having an acoustic dampening effect on sound waves impinging thereon.