Effects of otitis media with effusion (OME) on central auditory function.

Conductive hearing loss attenuates and delays sound passing through the middle ear. This impairs binaural hearing and other central auditory functions dependent on high fidelity sound transmission. Persistent conductive loss leads to central impairments that persist after the peripheral loss has resolved. For example, children who have had multiple episodes of otitis media with effusion (OME) in the first few years of life may have poor detection of sounds in noisy environments, evidenced by reduced binaural unmasking (BU). Recent research shows that a 'threshold' level of OME is required to produce impaired BU. Children who had OME in one or both ears for more than about 50% of the first 5 years had reduced BU. Animal research, using long-term ear plugging, suggests that total OME duration, rather than age at the time of having the disease, determines its effect on BU. Animals reared with bilateral (but not unilateral) ear plugs also have poor auditory temporal resolution, and reduced sensitivity to short tones in the presence of background noise, after plug removal. However, given time (6-24 months) and training, all animals regained normal temporal resolution.