A device and method for the continuous monitoring of otoacoustic emissions (OAE) levels on an individual worker uses as a pair of earpieces each featuring an external microphone, an internal microphone and a pair of miniature receivers. An adaptive filtering noise rejection processing of the measured distortion product OAE (DPOAE) is used to further improve the Signal-to-Noise ratio in frequencies where passive isolation remains insufficient. The adaptive filtering noise rejection technique relies on a Normalized Least-Mean-Square (NLMS) algorithm that uses the ipsilateral external microphone and the contralateral internal microphone to reject the noise from the measured DPOAE signals for each in-ear OAE probe. A DPOAE signal extraction algorithm provides for an increase in results reliability on a greater dynamic range in DPOAE magnitudes than known methods of DPOAE signal extraction. The device and method is suitable for the continuous monitoring of workers' hearing capabilities in industrial noises up to 75 dB(A).
