Protecting your Hearing at Protests

Audiology 101

Someone just reached out claiming their decibelometer read 117 decibels at the Lincoln protest. Please note if you are going to one of these protests, 117 dB means your 32dB foam ear plugs alone will not prevent hearing loss. If you add over the ear head phones too, then it might get you below the 85 dB threshhold that is considered to be the average threshhold for damage. But you may not be average! Hearing is a statistic as are the threshholds for hearing damage. It may be worth it to hire an audiological consultant who has access to a professionally calibrated decibelometer in order to get a true measure of the ototrauma being unlawfully inflicted (“disturbance of the peace/disorderly conduct”).

When you have noise induced loss, you lose hearing sensitivity to specific frequencies first, due to the snail-like shape of the cochlea. This means listening to speech is like reading a book that has had every instance of the letter k, t, s, and f removed, but everything else is the same. “Loud is still loud,” which means that if you have no hearing sensitivity below 80 decibels, if someone is shouting at you at 81 decibels, you’ll feel shouted at.

If you add foam ear plugs rated for 32 dB to over the ear headphones rated for 32dB, also, do not add the the decibel rating together. Decibels are a logarithmic scale. You don't have 64dB of ear protection with these two methods. At best, the combination might get you to about 40-42dB of protection. That would bring you below the average threshhold for hearing loss, but would not bring you below the threshhold for acoustic reflex firing (generally about 70 decibels), which causes a muscle in your middle ear to contract, which feels like you got poked in the ear drum. The actual sound pressure level doubles every 6 decibels, and your perception that it is twice as loud occurs at larger intervals of approximately 10 decibels. You are not a good judge of noise.

The problem is that eventually the noise is so loud it vibrates your skull (bone conduction) and this vibrates your cochlea from the inside. You are NOT getting used to this level of noise. It is bending hair cells, causing them to be inflamed, and this may lead them to die. They will not regenerate. Eventually, the noise so loud you're expecting sunglasses to protect your eyes from lava if all you’re doing is wearing foam ear plugs.

Sound is also a wave and waves follow the inverse square law. If you double the distance from the source of the wave, the intensity is 25% of the original intensity (i=1/d^2). You can use this information to advocate for the police separating you from the counter-protestors by a specific distance relative to the noise they intend to produce. There is also an “upward spread of masking,” which is why lower-pitched male voices drown out higher-pitched female voices. Therefore, if the police does not protect your mutual quiet enjoyment in a public space, this is a denial of your rights on the basis of your sex. The police have a right in the US to not help, but they don’t have a right to differentially help or not help. They do not have the right to discriminate.

Finally, if you have a connective tissue disorder, such as Ehlers-Danlos or Marfan's, excessive noise can physically damage you. Your middle ear bones have the same hypermobile joints and your tympanic and basilar membrane are made of connective tissue. The noise is further traveling throughout your body. Retinal detachment from forces being applied to the eye is a real thing that happens with connective tissue disorders, and this and other injuries can and do happen to people with connective tissue disorders especially who are exposed to excessive noise or other violence. Please protect yourself.