Evoked OAEs
OAEs are currently evoked using three different methodologies. Stimulus Frequency OAEs (SFOAEs) are measured during the application of a pure-tone stimulus, and are detected by the vectorial difference between the stimulus waveform and the recorded waveform (which consists of the sum of the stimulus and the OAE). Transient-evoked OAEs (TEOAEs or TrOAEs) are evoked using a click (broad frequency range) or toneburst (brief duration pure tone) stimulus. The evoked response from a click covers the frequency range up to around 4 kHz, while a toneburst will elicit a response from the region that has the same frequency as the pure tone. Distortion product OAEs (DPOAEs) are evoked using a pair of primary tones and with particular intensity (usually either 65 - 55 dBSPL or 65 for both) and ratio . The evoked responses from these stimuli occur at frequencies mathematically related to the primary frequencies, with the two most prominent being (the "cubic" distortion tone, most commonly used for hearing screening) and (the "quadratic" distortion tone, or simple difference tone).
Read more about this topic: Otoacoustic Emission
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