OAE (DPOAEs) was measured in both ears (excluding ears with middle ear pathology, eg, otitis media) on the day of admission (day 1), days 2 and 3, and between days 5 and 7 and 10 and 14. Patients were followed up in the outpatient clinic at least 30 days after discharge. OAEs were recorded using the Interacoustics Titan DPOAE 440 module. Eleven frequencies were measured in each ear: 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, and 10 kHz. The frequency ratio (f2/f1) was fixed at 1.22. OAE was performed with patients lying down with a 30° tilted head position. Frequencies were categorized as low (1, 1.5, 2 kHz), mid (3, 4, 5 kHz), mid-high (6, 7, 8 kHz), and high (9, 10 kHz). The emission threshold level (ETL) in each frequency category was calculated as the mean of the included frequencies.
A signal-to-noise ratio (SNR) of +3 dB was applied to the noise floor in low to mid-high frequencies and +6 dB in high frequencies. The distribution of final noise floor, and thus border of OAE detection, within each frequency category was low −10 dB, mid −15 dB, mid-high −13 dB, high −16 dB [28 (link)].
A signal-to-noise ratio (SNR) of +3 dB was applied to the noise floor in low to mid-high frequencies and +6 dB in high frequencies. The distribution of final noise floor, and thus border of OAE detection, within each frequency category was low −10 dB, mid −15 dB, mid-high −13 dB, high −16 dB [28 (link)].
