The greater the noise intensity, the more severe and faster the hearing loss, and the incidence of noise hearing loss increases exponentially with the increase in noise intensity. If the noise intensity reaches 55 dB, there is generally no hearing loss, and about 65% of 10 dB will cause hearing loss. 130 Above dB can cause irreversible hearing damage.
When the noise intensity is the same, high-frequency noise has a heavier impact on hearing than low-frequency noise; narrowband noise and pure tone noise have a greater impact on hearing than broadband noise; impulse noise is more harmful than steady-state noise.The sudden appearance of noise is more damaging to hearing than the gradually appearing noise.Continuous exposure is heavier than indirect exposure damage; the longer the exposure time, the heavier the damage, the 8 hours exposure produces a temporary threshold shift of 75 dB, and the 2-hour critical intensity is 85 dB.The longer the service, the heavier the loss.Long-term adherence to protective measures can greatly reduce noise damage.It is related to factors such as neuroendocrine changes in the body, high blood pressure, abnormal lipid metabolism, magnesium deficiency, and iron metabolism disorders.
Most inner ear diseases are more sensitive to noise, and those with progressive hearing loss should avoid working in noise workshops.There are diseases in the sound transmission mechanism of the middle ear, which can reduce the energy entering the inner ear, thereby reducing the damage to the inner ear by noise, but when the middle ear muscles are paralyzed, the inner ear is more susceptible to damage.