Structural Cochlear Changes After Noise Exposure

Excessive noise stimulation is known to cause either temporary or permanent hearing losses by damaging the sensory hair cells and associated structures in the cochlea of the inner ear.The nature of this damage, its extent and location, are determined by the intensity, freQuency and duration parameters of the noise exposure.During the initial, dynamic phase of the damaging process, changes occur at the cellular level; they may be temporary and recover, or they may later become permanent.Both degenerative and repair processes need time for completion and this will vary from a few hours to weeks or even months.When these processes have finished.an apparently static phase is reached.But in reality even during this phase, small changes may still be proceeding.Thus a study of permanent hair cell loss in relation to noise dose can be a valuable measure in trying to prevent noise induced hearing loss in humans.