Headphone system 30, which may be in-ear (figure 2), includes first and second earpieces 110a, 110b each comprising an electrode 112a, 112b. These measure electrical signals generated by a user in response to auditory stimulus provided by the headphones. The electrodes may comprise conductive, flexible material, such as pads 36a & 36b, preferably having an impedance less than 5kΩ and possibly made from silver-aluminium silicone. The electrodes may also be attached by hook and loop, adhesive or stitching. A third electrode 32 may be connected to a headband 34 for contacting a users scalp via protrusions 33, or may be integrated in a lanyard or cord of the system or held by the user in use. The system can be used to perform Auditory Evoked Potentials (AEP) tests detecting change in hearing response and a corresponding method, which includes comparing electrical characteristic at first and second times, is also disclosed.
