Hearing impairment in relation to viscoelasticity of middle ear effusions in children.

Both dynamic viscosity (eta') and elasticity (G') of middle ear effusion were measured with an oscillating sphere magnetic rheometer and compared with the degree of conductive hearing loss in 65 ears of 40 children. There was a significant correlation between eta' and the magnitude of the air-bone gap at 500 and 1,000 Hz, but there was no significant correlation between eta' and the magnitude of the air-bone gap at 2,000 or 4,000 Hz. No significant correlation was noted between G' and the magnitude of the air-bone gap at 500, 1,000, 2,000, or 4,000 Hz. These results indicate that the eta' of middle ear effusion has an effect on the amount of hearing impairment at frequencies below 1,000 Hz.