Audiometric Screening Protocol for Hearing Impairment

After otoscopic examination and immittance audiometry, each patient was seated within a double-wall, sound booth that complies with ISO 8253 and in the window view of the examiner but not of the audiometric controls board. Audiological screening of each subject was carried out using a Type 1 two-channel diagnostic audiometer (MADSEN Astera 1066 type, GN Otometrics A/S) and managing data using integrated OTO suite software. The examiners followed the Hughson-Westlake method of obtaining air conduction thresholds for each ear. The four frequency (0.5 KHz, 1 KHz, 2 Khz, 4 KHz) pure tone average threshold (4fPTA) was computed for both ears and then the better ear 4fPTA of each participant was used for statistical analysis. According to the WHO’s Grades of hearing impairment ¹³ , a 4fPTA ≤ 25 dB HL means no impairment, 26 dB HL ≤ 4fPTA ≤ 40 dB HL mild impairment, 41 dB HL ≤ 4fPTA ≤ 55 dB HL suggests moderately-severe impairment, 56 dB ≤ 4fPTA ≤ 70 dB indicates severe impairment and a 71 dB HL ≤ 4fPTA < 90 dB HL represents profound impairment.