Biologic bases of noise-induced hearing loss

The effects of noise are pervasive, and pathology can be found in the neural, sensory, supporting, and vascular cells of the cochlea after certain noise exposures. Several issues need to be addressed. First, what is the source of the wide range of susceptibility seen in people and animals that have similar noise histories but markedly different response to noise? Does this suggest a genetic factor in susceptibility to NIHL? Second, given the complexity of the biologic changes following noise exposures, it is difficult to predict the underlying pathology from standard audiologic tests. However, it would be desirable to distinguish sensory and neural and strial pathology because it is likely that the success of any aural rehabilitation will depend on knowledge of the type of pathology. This chapter focuses on a number of the traditional issues surrounding NIHL. However, one of the most exciting recent findings that undoubtedly will affect people with NIHL is that it is possible for sensory cells to regenerate. Research into the fundamental biochemical processes responsible for inducing regeneration is being pursued at a number of laboratories. The hope is to be able to repopulate the mammalian sensory epithelium with viable sensory cells.