Electrocochleography (ECochG) refers to the general method of recording the stimulus-related potentials of the cochlea and auditory nerve. The product of ECochG—the electrocochleogram, or ECochGm—is shown in Figure 1. As depicted in this figure, the components of interest may include the cochlear microphonic (CM), cochlear summating potential (SP), and auditory nerve action potential (AP). Detailed descriptions of these electrical events are abundant in the hearing science literature and are beyond the scope of this review. For a more thorough discussion of the history of these potentials as recorded in humans, see Ferraro (2000).

Figure 1..  

Components of the click-evoked human electrocochleogram. Top tracings display responses to rarefaction (R) and condensation (C) polarity clicks. Adding separate R and C responses (middle tracing) enhances the cochlear Summating Potential (SP) and auditory nerve Action Potential (AP). Subtracting R and C responses (bottom tracing), enhances the Cochlear Microphonic (CM). (From American Speech-Language-Hearing Association, 1988, p. 9, based on data from Coats, 1981.)

The popularity of ECochG as a clinical tool emerged in the early 1970s, following the discovery and application of the auditory brainstem response (ABR). The development and refinement of noninvasive recording techniques also has facilitated the current clinical use of ECochG.

The technical capability to record cochlear and auditory nerve potentials in humans has led to a variety of clinical applications for ECochG. Among the more popular applications are