Noise and Noise-Induced Hearing Loss (NIHL)

When considering noise in relation to sound, what is commonly meant is meaningless background sound of greater than usual volume. However, in the study of the effect of noise on health, the “noise” may mean any traumatic sounds (such as weapon noise in the field and narrowband noise or even pure tones at high intensity used in animal experiments in the lab to induce cochlear disruptions) and unwanted sounds (such as loud music from neighbors). Recently prolonged exposure to noise at the environmental noise level has been found to induce hidden hearing loss (cochlear injuries without a detectable hearing loss) and is receiving more attention. While some drugs and chemicals are known to produce hearing loss they are not covered in this chapter.