Swept - Tone Evoked Otoacoustic Emissions: Stimulus Calibration and Equalization

of a thesis at the University of Miami. Master’s thesis supervised by Professor Ozcan Ozdamar. No. of pages in text. (53) Otoacoustic Emissions (OAE) are minute acoustic responses originating from the cochlea as a result of an external acoustic stimulus and are recorded using a sensitive microphone placed in the ear canal. OAEs are acquired by synchronous stimulation with an acoustic click or tone burst and recording of the post-stimulus responses. This method of acquiring OAEs is known as transient evoked otoacoustic emissions (TEAOE) and is commonly used in clinics as a screening method for hearing and cochlear functionality in infants. Recently, a novel method of acquiring OAEs utilizing a swept-tone, or chirp, as a stimulus was developed. This method used a deconvolution process to compress the swept tone response into an impulse or click-like response. Because the human ear does not hear all frequencies (pitches) at equal loudness the swept-tone stimulus was equalized in amplitude with respect to frequency. This equalized stimulus will be perceived by the ear as equally loud in all frequencies. In this study a new hearing level equalized stimulus was designed and the OAE responses were analyzed and compared to conventional click evoked OAEs. The equalized swept-tone stimulus evoked greater magnitude OAE responses when compared to the conventional methods. It was also able to evoke responses in subjects that had little TEOAEs which might fail conventional hearing screening.