Folks say that sight is our most precious sense as human beings. While that may be true in every day life, I’d argue that unless you’re making silent films, the loss of hearing has a filmmaker unable to immerse their audience in their story – or be able to know if they are. Let’s cover the 4 quickest ways to lose your hearing, because most people get this wrong – and are damaging their hearing every day.
We can argue all day about whether you’d rather be deaf or blind, but I’d know which one I’d take. Many studies suggest that it’s far more isolating and maddening to be deaf than blind, and for certain, the kind of isolation deaf people feel is brutal. Part of this is because of the near 2,000 times more data that your aural pathways receive over your visual data bandwidth. Your brain uses sound as a guide to immerse itself in the world and connect with it. It’s why on Cinema Sound we stress the importance of knowing the art of using sound effects, foley and ambiences to create an immersion to replace what viewers’ brains are experiencing in a theater or even in an airport while they watch your show on iPhone headphones. It’s about immersion. But if our hearing mechanisms are damaged or broken, the ability to discern if your media is up to snuff and can compete becomes foiled.
We want to be able to protect our hearing mechanisms from the four ways to lose your hearing listed below at any cost including the cost of: embarrassment, inconvenience and expense. I suggest to everyone that you should Always Carry Earplugs with you, Always. I caveat this with “if you live in an urban environment.” If you’re out in the toolies, well, loud sounds which damage hearing (except for things like gunfire and machinery) just don’t happen in the wild. But if you live in a city, chances are you’re exposed to one or more of these issues daily.
Look, there’s current emerging technology which can help you hear better if you’ve damaged your aural mechanism: hearing aids, surgery which bores into your skull and connects to the aural nerve with different physical mics installed, but there’s nothing currently available which can fix the actual biological hearing system. The first solution, although helpful, further damages the mechanism, and the latter bypasses it altogether. THERE IS NO LASIC FOR YOUR EARBALLS.
How Does It Work?
The human hearing mechanism is a brilliantly devised system which acts much in the same way as a microphone:
- Head = Microphone Stand and Clip
- Outer Ear = sort of a “windscreen” and a special parabolic reflector which your brains learns over time to discern where sound is coming from
- Eardrum (or the appropriate Cinema Sound term “Earballs”) = diaphragm of a microphone
- The bones in the ear = diaphragm housing and back plate
- Cochlea = the only part that isn’t like a microphone
- Aural Nerve = cables in the mic which takes the voltage made from the back plate to the XLR connector on the end.
All of these but the Cochlea are pretty straightforward. But the Cochlea, that’s the part that is the asset and liability of the ear. It’s the most sensitive audio sensor ever devised, but it’s also the most delicate. Filled with microscopic hairs in the snail-shaped organ, each hair corresponds to a particular frequency in the hearing spectrum. If you lose one of these hairs they do not grow back. You’ve lost the ability to be sensitive to that frequency. Small hairs are in the front for high frequencies and longer hairs for low frequencies are in the back. Once the hair vibrates sympathetically with a frequency, it sends a small voltage down the aural nerve to the brain. Nice.
What do we need to watch out for?
Loud, sharp, transient sounds literally rip the hairs out of the cochlear organ. The body has no time to create Temporary Threshold Shift (talked about below) and the ear is at normal sensitivity receiving this blast of pressure. The strong over pressure of air smashes into the earballs and can even fracture the ear bones, but the result is catastrophic for the delicate and sensitive hairs in the cochlea. Examples of this are gun shots, 2X4 pieces of wood smacking together, and even single isolated hand claps at close range. This is the quickest way to damage your hearing. Those who have served in the military, thank you for your service.
Since the hearing mechanism is located in the head, a blow to the head will also damage the entire hearing apparatus. Bones can be fractured, cochlear hair loss, ear drum rupturing and even more destructive is when the plates of the skull shift and pinch the aural nerve. All of these can cause serious and irreparable damage. Also, lest we forget, you poke yourself in the ear with a sharp stick – or mash enough ear wax against your earballs with q-tips that you block the free flow of sound pressure, this will also significantly impede your ability to hear well.
Disease and Tumors
There are a few nasty diseases out there which will rob you of your hearing, but there are fare more pharmaceutical drugs which will: Antibiotics, pain killers and of course recreational drugs can and significantly and permanently rob you of your hearing. One of the tests we performed on attendees of Sound Advice was to listen to spatterings of frequencies throughout the hearing spectrum in order to see who had the most sensitive hearing to high frequencies. Babies can typically hear 20,000 Hz, and we lose this sensitivity as we grow older. You can do this test on your own with a DAW which has a sine wave oscillator. It’s normal for someone 60 years old to not be able to hear 13,000 Hz. It’s not great, but it’s normal. If you’re 45 and can’t hear 13K, then you’ve either been exposed to loud machinery for a job, firearms, lived a good life of loud rock concerts or clubbing, or you have a biological issue. That biological issue may be serious, but it usually isn’t if you’re not also experiencing headaches, nausea, and other neurological issues. I’M NO DOCTOR, nor am I advising you medically IN ANY WAY. And, if can’t hear 13K, and you’re under the age of 55, and you didn’t serve, hated rock concerts and loud music, and didn’t work with a jackhammer for 30 years, I’d strongly suggest you get your hearing checked. They check for all kinds of things including tumors in the ear canal and more. It’s very rare. And it happens. Early discovery helps immensely.
This is the one which most people don’t think of. Long exposure to semi-loud sounds will cause powerful hearing loss. When the brain receives a loud sound it sends a signal to the ear to “tighten up” the ligaments around the bones and earballs so that it protects the delicate nature of the cochlea from further assault. This happens within a 1/10th of a second. This can last for hours. We call it TTS or Temporary Threshold Shift. You know you’ve had some TTS when your ears ring strongly and you feel “stuffed up” but you have no post nasal drip. You’ll also know you’ve had some TTS because you’ll remember you were just exposed to loud sounds. The feeling you have the next morning after a rock concert etc. Short exposure to loud sounds which aren’t transient are not a big deal. It’s why your body developed this system to protect your hearing mechanism. Of course, if you’re trying to mix and you’re in the middle of strong TTS, it’s bad. Real bad, because you’ve had a serious hit to your ability to be sensitive to frequencies between 7-14kHz. Moreover, if you’re mixing for a feature film at 85 dB for 12 hours, I promise your mixes aren’t going to be that good. I talk about how to get around this in the MZed Pro Membership Education.
OSHA has standards for this in the workplace, but I think they’re too lenient. I like to halve them. Here’s Mark’s rule of thumb for maximum exposure:
- 80 dB: = 8 hours
- 90 dB: = 2 hours
- 100 dB: = 30 minutes
- 110 dB: = 7 minutes
- 120 dB: There should never be exposure here.
If 125 dB is the level of pain, where you’re experiencing physical pain in your skull, then how loud is everything else?
Well, as you can see from these charts, sound is on an exponential scale, which means that a sound at 90 dB is twice as loud to your earballs as an 87 dB one. If 150 dB is where your earballs physically tears off your skull, you can see why you don’t want to be in a tornado, and you’ll immediately understand why Dorothy had to be profoundly deaf in OZ.
In my Mazda 3 at 80 mph on asphalt, the interior cabin volume is 79 dB. On cement it’s 84 dB. On different pavements, there’s a substantial difference while driving. I also ran a loudness test on a plan I was on not too long ago. 89dB. Ouch. Now, I was at the end of the plane right behind the engine, but that might account for 3-4 dB. So, what happens when you’re on a flight from LA to London for 11 hours? Yep. Everyone on that plane has experienced hearing loss. Always wear earplugs on a plane. It also helps with jet lag I’ve found.
I’ll say it again, there’s no LASIC for your earballs. Always carry earplugs always. I plan on being able to hear 13,000 Hz well into my 60s. I hope to be listening to 12,500 Hz tones with you then too.
Have your own hearing loss story or experience? Let us know, or Tweet about it!