Noise-canceling headphones have become wildly popular over the last few years. They are now widely available and more effective and affordable than before. Whether you want to drown out the noises of the world or simply enjoy music better, a pair of these headphones should do you wonders. However, don’t be surprised if they also produce undesirable side-effects such as headaches, ear pain, and a feeling of “pressure” in the inner ear. So, why are ANC (active noise control) headphones so uncomfortable? As it turns out, it may have more to do with the brain than the headphones!
Instead of blocking out external noise, ANC headphones cancel it out.
To know why noise-canceling headphones hurt your ears, you must first understand how ANC or active noise control technology works. Unlike the fluffy earmuffs that you wear at a shooting range for ear protection, noise-canceling headphones do not block out noise. Instead of shielding your ears against external sound waves, ANC technology cancels them out. Here’s how it works:
Sound travels in waves just like light does. We see the different light frequencies as colors, and we hear the different sound frequencies as pitches. Now, unlike light, sound waves are “pressure waves,” which can move through objects such as water, walls, or a set of plastic headphones. Low-frequency waves are better at moving through solid objects than high-frequency waves. That is why ANC technology aims at eliminating low-frequency sounds.
Noise-canceling headphones use a built-in microphone to monitor your environment and identify noise frequencies. ANC technology then releases anti-noise waves to cancel out the unwanted external sound frequencies. The anti-noise waves are of the same pitch as the external noise, but they have a reversed polarity. When two sound waves of opposite polarities collide, they cancel each other out.
The anti-noise waves themselves do not cause headaches or the feeling of “pressure” in the ear.
After learning about how ANC technology works, you might assume that the anti-noise waves are what causes your ears to hurt or experience the pressure. You might even liken the sensation to airplane ear or ear barotrauma, which you might have experienced when traveling by air. Earth’s gravity is constantly pulling on the atmosphere, which is why low-altitude areas experience denser air pressure than high-altitude areas. However, atmospheric density is not responsible for causing painful sensations. Ear barotrauma occurs when the air pressure in your environment is different from the air pressure in your middle ear.
When you are at a high altitude (for example, inside an ascending airplane), your middle ear wants to release air. However, when you are closer to gravity, your ears need more air. “Popping” your ears equalizes the air pressure in your ears and the surrounding environment, eliminating the uncomfortable sensation.
Noise-canceling headphones are not designed to create pressure in your ears, but the brain mimics the sensation.
Headaches and ear pain are not the only factors telling the brain about changes in atmospheric pressure. Ear vibrations are also good indicators. When you are inside an ascending airplane, and the air density in your middle ear is higher than the air pressure outside, the ear does not vibrate much, which leads to reduced low-frequency hearing. As a result, the brain perceives decreased low-frequency hearing as a sign of changes in atmospheric pressure.
As we discussed above, noise-canceling headphones are designed to cancel out low-frequency sound waves. When that happens, the brain automatically assumes that there is a change in air pressure and produces the sensation of pressure or pain. However, since your headphones are purposefully eliminating low-frequency sound waves, popping your ears will not provide relief. The longer you wear the headphones, the more severe the sensation may get.
That is why if you are especially sensitive to airplane ear, you might want to steer clear of noise-canceling headphones!