However, use of earplugs is only effective if the users have been educated and use them properly without proper use, protection falls far below manufacturer ratings. Earplugs and earmuffs can provide the wearer with 10 dB to 40 dB of attenuation. Passive ear protection includes earplugs or earmuffs which can block noise up to a specific frequency. Personal noise reduction devices can be passive, active or a combination. Physiological response Personal Noise Reduction Devices The contractile effect of the outer hair cells, activated by the efferent nervous system has been proven to provide a protective effect against acoustic trauma. This “protective effect” had long been thought to involve the active mechanisms of the outer hair cells and the efferent system commanding them. This âprotective effect” only happens if the traumatizing noise is presented within an optimum interval of time after the sound-conditioning session. The same “protective effect” was also observed with other stressors such as heat-shock conditioning and stress conditioning.
It had been observed that noise conditioning several hours prior to the exposure to traumatizing sound level, significantly reduced the damages inflicted to the hair-cells. The cochlea is partially protected by the acoustic reflex, but being frequently exposed to noise does not lower the reflex threshold. The ear can not get more resistant to noise harmfulness by training it to noise. Expert Chat: What to Know About Sudden Hearing Lossĭespite different people having different thresholds for what noises are painful, this pain threshold has no correlation with which noises cause hearing damage.
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