Could you make a speaker “play” noice canceling to make a cafe, or other noisy enviroment quiet?
Also, could this be used in another interesting way?
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Yes, this technology is commonly used in office environments. It’s called noise masking. It’s the same essential concept as a white noise machine and sounds a bit like an HVAC system blowing air.
There are more advanced versions used in secure rooms, often in tandom with EM signal blocking and extreme acoustic damping insulation.
Yes. It’s possible although the bigger the area the harder it is.
White noise is a lesser version of this, but is commonly used in offices.
Noise canceling works on the principle of using a microphone to collect information about sound waves and then play sound waves that cancel them out.
You could theoretically speaking use noise canceling on sound coming from outside the room. It would be impossible to use it on the noise being created inside the room.
No, not really. Noise cancelling relies on being able to play the “opposite” sound to cancel out the sound waves before they reach your ear. It works well for headphones only because the microphones that pick up the ambient sound to determine the cancellation signal are basically in the same place as your ears, and the headphone drivers. With everything in the same place, the circuitry basically just has to invert the polarity of the ambient noise signal as received by the microphones, and maybe time delay it ever so slightly if the electronics can process the signal from the microphones faster than the actual ambient asound wave can travel from the outside to the inside of the headphone cup.
With speakers it wouldn’t be feasible to get an “anti” signal to line up nicely with the ambient sound signal because it all depends on your positioning and the relative time it takes the sound waves from the speaker to reach you vs from the ambient sound sources. Also the noise canceling signal played by the speaker would be picked up by the microphones, so it would keep trying to “cancel itself”, so to speak
Theoretically, possible but it would be very difficult and the result is very likely to be uneven.
Active noise reduction relies on creating a counter sound pressure to reduce the amplitude of the “noise” signal. The problem is this noise is not even across large spaces and reflecting surfaces, moving furniture and people etc all serve to reflect noise sources. It would be very difficult for a small number of speakers to counter this throughout the space (and the system would have to “measure” or calculate the direct and reflected noise at all points in the space and then somehow calculate a counter wave.
It could most easily do so for some low frequency constant noise perhaps. But the worst case might be suppressing the noise in one area only to amplify said noise in another if the “cancelling” wave reinforces the noise instead.
Yes, you can use noise canceling on a speaker to reduce background noise and create a quieter environment, like in a cafe
It could also be utilized creatively for immersive gaming or studying in noisy places!
everyone here is commenting it’s not possible, but luxury cars already have it.
but to be fair, they work best for repeating patterns like tire noise and wind noise, unlike noise cancelling headphones, which can suppress uneven sounds like someone speaking (reasons were provided by others)
I’m having the ridiculous idea of using speakers to cancel out tire noise of cars/trucks for people OUTSIDE of the car. Think of it like a speaker/microphone-combination, sitting directly at the source of the noise – at the wheels. Must be a really powerful speaker system, but since tire noises are mostly high pitched sounds, the diameter doesn’t have to be that big.
Gave away my billion dollar idea with this, but it probably wouldn’t work and I’m too lazy to develop it, anyways. Living in a world without street noise still would be definitely worth staying poor.
When you fill something with water, like a glass, and watch the edge where the water is along the glass it makes a line. If you cause ripples in the water, that line along the edge goes up and down. Sound going into your ear is kind of like that line, a single feed travelling into your ear canal.
Noise cancelling headphones take that single source of sound going into your ear, and for every high part of the wave, it counters with a low wave and vice-versa. This is how it cancels noise for your ear specially.
Move that noise cancelation device away from your ear, and it ceases to be a simple line of sound. Now it is the entire surface of the glass of water. Now you have multiple points of sound occurring in multiple locations.
Take three drops and drop it in the water. Each drop causes a ripple effect outward from where it entered the water’s surface. When the ripples of multiple drops meet, the highs become higher and the lows become lower while the highs and lows negate each other at each specific point on the surface. Across the entire surface, simultaneously, the interactions are happening in different ways.
It would be impossible for a single speaker to emit a single sound from, yet another point on that surface (another ripple), that would travel outward with the right pattern of highs and lows to negate every other ripple, because it is itself only a single ripple.
It would be like you dropping a single drop of water into the rippling surface and having that extra drop bring the entire surface to a flat standstill. It won’t happen.
The only option would be to create so much disruption on the surface that you can no longer isolate a single drop’s ripples. This is what white noise does, floods the sound you hear with other sound to disrupt your ear from hearing a particular one. But that single sound isn’t outright cancelled, just diffused in the other noise.
The wavelength of sound plus the geometry of the room would make things impossible.
Active noise cancelling works by superimposing a wave that is exactly out of phase with respect to the original sound. This perfect superposition needs to happen at the listener’s ear.
Notice however that just by moving a tiny bit closer to the speaker than to the origin of the noise, or viceversa, you can ruin this phenomenon. The wavelength of sound is around 1 centimeter, so really a tiny movement would completely destroy your cancellation.
With earplugs this is not a problem because noise and canceling sound are coming in from the same hole in your head, so you can tune the cancellation exactly.
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