**3.2 The compound action potential (CAP)**

Although single-fibre recordings provide much information, the amount of data that can be generated in an individual gerbil, especially in aged animals, is limited. An alternative to evaluate the state of the cochlea is the compound action potential (CAP), an electrical signal that is generated by the synchronised population response of the auditory nerve fibres to the onset of a signal (Hellstrom & Schmiedt, 1996).
