not really an but I can understand 120dB being harmful if you get exposed to it for a second but 90dB has to be over a 2 hour time exposure to get hearing loss.
Why is time a factor and what mechanism causes hearing loss upon being exposed to high decibles
In: 2
Sound are waves that travel across the air. Maybe an analogy to other types of waves like earthquakes or sea waves is easier to understand.
A big wave can swiftly destroy everything on its way, a smaller wave won’t destroy everything , but can still cause some damage. Exposure during long time allows this damage to accumulate and there’s a point where your body can no longer repair it. I am too ignorant to provide a more detailed answer.
So, when a soundwave hits your eardrum, it causes little bones to vibrate against your cochlea which has little hairs in it. The vibration of the hairs is what triggers the signal to be sent through your nerves to the brain so that you can hear it.
Those hairs don’t regrow, so if they get vibrated too much and fall out then your hearing gets worse until you run out and are deaf.
So while 90db isn’t particularly traumatic for those hairs, continued exposure to that level of vibration can damage them over time.
Imagine giving a high five. Your hand is fine after one, but if you were to give high fives for 2 hours your hand would be red and swollen. Something that isn’t necessarily damaging for a short period can add up to a lot of damage over time.
Does it do more or less damage if you get punched once or if you get punched every second for two hours? It’s exactly like that with pretty much every sort of thing that damages your body via exposure – there’s just plain more energy being imparted to screw things up the longer the dangerous condition is maintained.
Latest Answers