Improved hearing conservation in industry: More efficient implementation of distortion product otoacoustic emissions for accurate hearing status monitoring

Abstract

Preventing occupational hearing damage requires close monitoring of workers' hearing. Implementing Distortion Product Otoacoustic Emissions (DPOAEs) in-field is a sensitive and feasible approach provided that a combination of minimal measuring time and infrequent false-positives—i.e., cases where elevated background compromises DPOAEs—is found. This paper investigates how measurement time can be reduced by carefully selecting the tested frequency span and resolution, and how false-positives are minimized by comparing DPOAEs acquired in noise with DPOAEs previously obtained in optimal test conditions. To test this, DPOAEs have been registered with a 1/8-octave band resolution from 841 Hz to 8 kHz for 60 subjects, in quiet conditions and in white noise levels ranging from 54 dB(A) to 90 dB(A). Measurement accuracy is confronted to decrease the measurement time as a function of frequency resolution and range. Diagnostic importance and sensitivity to background noise is addressed for different frequency regions. Within-subject variation of DPOAEs in noisy conditions is assessed both between different noise conditions and between subsequent probe placement. Obtained test–retest statistics quantify normal variability and allow within normal working routines to select for further investigation persons with DPOAEs falling outside this range.