The over-exposure to excessive loud noise is partially attributed to recreational exposure, such as the use of personal audio devices with music at high volumes for long durations, or social settings such as bars, entertainment and sporting events.The International Organization for Standardization (ISO) developed the ISO 1999 standards for the estimation of hearing thresholds and noise-induced hearing impairment. They used data from two noise and hearing study databases, one presented by Burns and Robinson (Hearing and Noise in Industry, Her Majestys Stationery Office, London, 1970) and by Passchier-Vermeer (1968). As race and ethnicity are some of the factors that can affect the expected distribution of pure-tone hearing thresholds several other national or regional datasets exist, from Sweden, Norway, South Korea, the United States and Spain. In the United States hearing is one of the health outcomes measure by the National Health and Nutrition Examination Survey (NHANES), a survey research program conducted by the National Center for Health Statistics. It examines health and nutritional status of adults and children in the United States. While there is no perfect way to pinpoint hearing loss from excessive noise, researchers look for audiometric notches in a hearing test—dips in the ability to hear certain frequencies—as signs of possible NIHL. As of 2011 data, approximately 24% adults age 20–69 in the United States has an audiometric notch. This data identified differences in NIHL based on age, gender, race/ethnicity, and whether or not a person is exposed to noise at work.
While healing, an over-expression of glutamate receptors can result in temporary tinnitus, or ringing in the ears. Repeated ruptures at the same synapse may eventually fail to heal, leading to permanent hearing loss.Prolonged exposure to high intensity noise has also been linked to the disruption of ribbon synapses located in the synaptic cleft between inner hair cells and spiral ganglion nerve fibers, leading to a disorder referred to as cochlear synaptopathy or hidden hearing loss. This disorder is cumulative and over time, leads to degeneration of the spiral ganglion cells of the inner ear and overall dysfunction in the neural transmission between auditory nerve fibers and the central auditory pathway. The most common symptom of cochlear synaptopathy is difficulty understanding speech, especially in the presence of competing noise. However, this type of hearing impairment is often undetectable by conventional pure tone audiometry, thus the name "hidden" hearing loss. Acoustic over-exposure can also result in decreased myelination at specific points on the auditory nerve. Myelin, an insulating sheath surrounding nerve axons, expedites electrical impulses along nerves throughout the nervous system. Thinning of the myelin sheath on the auditory nerve significantly slows the transmission of electrical signals from hair cell to auditory cortex, reducing comprehension of auditory stimuli by delaying auditory perception, particularly in noisy environments. Individual susceptibility towards noise
There appear to be large differences in individual susceptibility to NIHL.