(2) Noise spectrum. Under the same intensity, high frequency noise is more harmful to human body than low frequency noise, and narrow band noise is more harmful than broadband noise. Spectrum can affect the degree of hearing loss, but it will not affect the high-frequency auditory valley of hearing loss.
(3) contact time and contact information. With the same noise, the longer the contact time, the more serious the hearing damage and the more people will be injured. In the above case, the enterprise where the patient is located implements three shifts, each shift is 8 hours. The peak value of impulse noise in the workshop is 1, 35.6 dB (A), and workers are exposed to impulse noise about 1500 times a day, which leads to serious hearing damage. In addition, continuous exposure to noise is more harmful to human body than intermittent exposure. In order to prevent noise hazards, the employer should establish a soundproof lounge and implement a rest system, so that workers can leave the workshop temporarily, shorten the time to accept noise and help restore hearing.
(4) The nature of noise. There are many ways to classify productive noise. In occupational health work, productive noise is generally divided into steady noise and impulse noise according to its duration and appearance. Impulsive noise is more harmful than steady-state noise. Under the same noise level, frequency spectrum and time, the incidence of deafness, hypertension and central nervous system dysfunction in workers exposed to impulse noise is higher than that in workers exposed to steady noise. The greater the peak sound pressure level, the longer the width, the more times, the faster the repetition rate, and the shorter the rise time of impulse noise, the greater the damage to the hearing threshold.
(5) Synergistic effect. If vibration, high temperature, cold or some toxic substances exist at the production site at the same time, the adverse effects of noise will be amplified, and the impact on auditory organs and cardiovascular system is more obvious than that of single noise.
(6) Health status and individual sensitivity. Under the same conditions, individuals who are sensitive to noise or people with certain diseases, especially those with ear diseases, may have obvious lesions even if they have short contact time or low noise intensity. This is related to heredity, physiological and biochemical metabolism, ear structure and social or psychological factors.