Canford has considerable experience in the design of headphone limiters and their use in the operational environment. Whilst virtually any headphone or headset can have a limiter fitted, using one of the seven types of standard multipurpose limiter circuits, this usually has to be in an in-line housing. By designing type-specific circuits for individual ear loudspeakers, these can be made small enough and appropriately shaped to enable them to be built into the earcup housing. Adding a limiter circuit to a headphone alters the input impedance.