Effect of pre-school sound exposure on children’s hearing function: results from preparatory studies assessing hearing function by distortion product otoacoustic emissions

This study investigated the potential impact of sound exposure in preschools on children’s hearing function by measuring distortion product otoacoustic emissions (DPOAE) over time. A longitudinal repeated-measures approach was employed to evaluate how DPOAE amplitudes varied with sound exposure and pre-school attendance duration, analysed using general estimation equation (GEE) modelling. The sample included 62 children aged three to six years attending preschools. Sound exposure levels and DPOAE amplitudes were measured during time being indoor. Average indoor sound levels (time indoors (_Ti)) were 81 dB LAeq_Ti, with highest noise events reaching 112 dB LAFmax. A total of 31 measurements (52%) exceeded 80 dB LAeq_Ti. GEE analysis showed a significant decrease in DPOAE amplitudes at 6 and 8 kHz in the right ear in relation to sound exposure levels, suggesting a sound level-dependent effect. Time spent in pre-school revealed a decrease in DPOAE amplitudes at 3 and 4 kHz in the right ear over the day and week, indicating cumulative effects of sound exposure. The findings suggest that pre-school sound exposure may adversely affect children’s hearing, particularly at higher frequencies and over time. Further research is needed to validate these results and explore long-term implications of early-age noise exposure.