After I posted my review on the ISOtunes Link Bluetooth earmuffs, there were a couple of questions and comparisons related to active noise cancellation devices. A similar question has also been posted in reply to my video review, and it seemed a post on the topic would be a good idea.
Note: This post contains my opinions, and should not be considered as professional health or safety advice.
In a nutshell, hearing protection products block out harmful noises. They provide a physical barrier that reduces the intensity of noise that enters your ears.
Hearing Protection with Bluetooth Connectivity
You also have hearing protection products with Bluetooth connectivity. Models equipped with microphones allow you to take phone calls while still wearing the products, and most allow for music streaming when wirelessly connected to a Bluetooth source.
Bluetooth hearing protection products also have limiters so that you cannot increase playback volume to hearing-damaging levels.
So, these products block out hearing-damaging noise, can enable Bluetooth headset-like communications, and allow for safe-hearing-level audio playback via Bluetooth streaming. Some models also have built-in radios.
Noise Cancellation Headphones or Earbuds
Apple’s AirPods Pro are an example of an in-ear product with active noise cancellation technology.
Hearing protection products block out noise. Active noise cancellation products counter it.
Active noise cancellation technologies use a microphone to pick up ambient sounds, and a speaker that produces its own noise equal amplitude and opposite phase. The result is destructive interference where everything cancels out – except your desired music or audio playback.
Hearing Protection vs. Noise Cancellation
Let’s say someone has a water blaster filled with water dyed with blue food coloring. You’re wearing a green shirt.
Hearing Protection Analogy
You hold up a rag in front of you, and it blocks most of the blue water from reaching your shirt. With a high-pressure water blaster, some of the blue-dyed water might make it through the rag and get on your shirt, but in small amounts that won’t ruin the shirt.
Active Noise Cancellation Analogy
Instead of holding a rag in front of you, you have your own water blaster filled with yellow-dyed water. Every time you’re blasted with blue water, you blast yellow at the same spot. The two water streams interact, and when mixed you have green. Since you’re wearing a green shirt, you don’t notice any spots with green-mixed water landed.
What Happens at Unsafe Levels?
Active noise cancellation technology does not block loud noises, it measures and counters them.
Noise cancellation devices are primarily designed for use at everyday safe noise levels. They’re not designed to counter unsafe noise levels, they’re designed to eliminate background noise, such as steady fan and HVAC sounds, mixed chatter on a train or plane, and things like that.
They might have difficulty countering unsafe levels of tool and jobsite noises, leaving you unprotected.
To perfectly cancel out noises, noise cancellation products need to emit their own noise waves out of phase with the incoming signal. There’s a limit as to how loud of a cancellation wave such products can emit. There’s the potential that muffled sound and playback sound could lead to unsafe noise levels during use.
Additionally, what happens when you run out of battery? You’re left unprotected. with hearing protection products, they block unsafe noise levels (to a degree) and then offer playback features on top of that.
Some people have shared positive experiences where they’ve used active noise cancellation technologies in lieu of hearing protection, but it’s risky.
There are headphone products that also block out some noise levels, due to having ear cups that surround your ear, but they’re not designed to block out harmful noise levels, and might not be as effective in doing so.
I haven’t seen studies that test active noise cancellation products with respect to hearing-damaging noise levels. Still, it cannot be assumed that they’re safe.
Active noise cancellation products must be charged, their microphones sensitive enough, their speakers must be capable of emitting a broad range of matching frequencies, and the response rate must be fast enough. And even then, there might still be factors that could potentially lead to hearing damage over time if used around unsafe noise levels in lieu of hearing protection.
Hearing protection products need to be replaced over time, and you have to use them as directed, but they simply work.
100 birds are perched in a tree, and you must stand under that tree. The birds are starting to do their business, one at a time. Would you rather protect yourself against the birds’ bodily functions with an umbrella, or by looking up and trying to dodge the falling droppings?
Noise cancellation tech has come a long way in recent years and they are quite effective at blocking out ambient sounds. But when it comes to harmful sound levels, can they be trusted?
My recommendation is to use hearing protection products when you need hearing protection.
This is a comparison I am still learning more about, but one thing is certain – the two types of products are very different and not interchangeable.
Could active noise cancellation (ANC) products be used for hearing protection? I don’t know. Maybe? But I wouldn’t trust them. If you disagree, show me why this is wrong.