Audiometry in Fluctuant Hearing Loss

Abstract

Fluctuant hearing loss is a very complex matter, which involves not only neurological and physiological concepts but considerable acoustic factors as well. Fluctuant hearing loss is perhaps more visible with the use of pure tone audiometry because of the nature of its effect, the variation in the compliance properties of cochlear tissues. This visibility is due to impedance factors that bear on the inner ear as well as on the middle and external ear regions. It is suggested that changes in compliance of the cochlear tissues play a significant role in the existence of reduced sensitivity to low frequency pure tones. This indicates that sensorineural conditions with loss of hearing in the low frequency region may be a composite of conditions: sensory cell damage, which is only seen by high frequency response, and disturbance in the cochlear tissues, increasing their stiffness and resulting in loss of sensitivity for low frequency tones. When hearing damage is found in the inner ear exclusively because of permanent destruction of sensory cells, this theoretical model predicts that the fluctuating nature of certain types of hearing impairment ceases.