BACKGROUND AND OBJECTIVES: A distortion product otoacoustic emission (DPOAE) is a non-invasive method which is commonly used to assess the hearing function of the cochlea and to reflect objective information of specific frequency in the cochlea. We hypothesize that after applying a broad band noise (BBN), the outer hair cell's function will change and cause reduction in the amplitude of DPOAEs and signal to noise ratio (SNR). SUBJECTS AND METHOD: We performed the examination on 40 subjects (80 ears) who have a normal hearing function. DPOAEs were recorded before and after BBN stimulation (intensity: 90 dB HL, duration: 10 minutes). RESULTS: After the BBN stimulation, the amplitude of DPOAEs and SNR were decreased at all frequencies. The amplitude of DPOAEs and SNR decreased 0.3-1.6 dB SPL, 0.6-1.5 dB SPL, respectively. Decreases in the amplitude had statistical significances after 3 and 6 minutes in 1 kHz, 3 and 6 minutes in 2 kHz, immediately after noise exposure, and after 3 and 6 minutes in 6 kHz. However, the SNR changes had statistical significance only after 3 minutes in 1 kHz. After the stimulation, pure tone threshold at 4 kHz increased 3.2+/-3.9 dB HL. After the BBN exposure, the amplitude of DPOAEs and SNR decreased at all frequencies and most of them recovered within 12 minutes. CONCLUSION: These results suggest that DPOAE could be a clinically useful method for the purpose of screening, managing and assessing the prognosis of acoustic trauma and noise induced sensorineural hearing loss.
Auditory Fatigue ; Cochlea ; Hair ; Hearing ; Hearing Loss, Noise-Induced ; Hearing Loss, Sensorineural ; Mass Screening ; Noise ; Prognosis ; Signal-To-Noise Ratio