4 ms·

This won't work. In addition to what others have said about different points in the room having different distances to the fan and speaker, there are other issu

This won't work. In addition to what others have said about different points in the room having different distances to the fan and speaker, there are other issues: 1. The fan's fundamental frequency isn't perfectly stable, so even if you are in a spot where there speaker's tone cancels with it, the fan will probably wander around that frequency enough that the cancellation won't work well. 2. The fan isn't just a fundamental tone + noise. There are also a whole series of harmonics above it. You'll need to cancel those out too. Even if you do cancel out the fundamental, you'll still "hear" it because of the missing fundamental effect [1] otherwise. Cancelling those overtones out gets harder and harder because the higher the frequency, the more precise you need to be with phase to get proper cancellation. 3. Obviously, none of this will help with the atonal noise components of the fan's sound, which are significant. Though arguably, if you get rid of the droning tonal part, the remaining whooshing noise might actually be a nice sound. I believe the most effective fixes here are: 1. Get a better, quieter fan that produces less noise to begin with. 2. Move the fan farther away. You don't necessarily need to filter the air from the window closest to you. Put it in a farther window. Or go all the way and get a whole house fan that puts the fan in the attic. [1]: https://en.wikipedia.org/wiki/Missing_fundamental https://en.wikipedia.org/wiki/Missing_fundamental

jsenn 1y ago
Is the drone of a fan harmonic? I would’ve thought it’s more like a repetition pitch so its overtones would not be harmonic and would not exhibit a missing fundamental. Agree with the broader point, just curious if there’s some interesting physics that creates a harmonic sound.
- munificent 1y ago
  > Is the drone of a fan harmonic? Overtones are about timbre, not harmony. The fan isn't playing a chord (well, probably not). But the tone the fan plays isn't a pure sine wave either. It will have overtones that are integer multiples of the fundamental that give it its characteristic sound. It's the same reason that a flute and saxophone can play the same note but sound different. The fundamental is the same, but the amplitudes of the overtones are different.
  - jsenn 1y ago
    > It will have overtones that are integer multiples of the fundamental that give it its characteristic sound. What I’m wondering is why would the overtones go in integer multiples (I.e. be harmonic) for a fan? A flute and a saxophone have harmonic(ish) overtones because of the physics of a vibrating column of air
    - ejoso 1y ago
      So are you saying the only difference between a woodwind instrument and a fan is the column? What about a stringed instrument then? Every sound found in nature contains multiple frequency components. When these align as integer multiples of the fundamental, they are harmonics; when they do not, they are inharmonic partials. Only a pure sine wave lacks them, and such signals don’t occur naturally.
      - jsenn 1y ago
        A string fixed at both ends produces harmonic sounds because of its particular structure. In order to have a non-integer overtone the ends would have to move up and down, which by construction they can't. Similarly for wind instruments: the air stops at either end and is reflected back, and a non-integer overtone would require changing the length of the tube (or sticking holes in it to allow the pressure to go to zero at the hole, effectively creating an artificial "end" of the tube). By contrast, a freely vibrating bar (not fixed at the ends) does not have harmonic overtones. To make the bars of a xylophone, marimba, or vibraphone sound nice, you have to cut out a little "scoop" shape from the bottom of the bar to force it to vibrate such that its overtones match up with integer multiples of the fundamental frequency of the bar. As you say, most sounds in nature do not have a harmonic spectrum, so if a fan did I would find that surprising and interesting.
    - ssivark 1y ago
      > why would the overtones go in integer multiples (I.e. be harmonic) for a fan? The fan noise is from its own vibrations -- presumably driven by the motor. These vibrations will correspond to natural vibrating modes on the body of the vibrating object -- which could be the motor, or the chassis, or even possibly the fan blades. Whatever the shape, the natural modes will be naturally quantized into "harmonics". Those vibrating modes could have more nuanced spatial forms (eg. Bessel functions) but their temporal pattern would likely be sinusoid.
renox 1y ago
I wonder if it wouldn't be better to have two fans: one at a high position and one at a low position.
NoNameHaveI 1y ago
"1. Get a better, quieter fan that produces less noise to begin with. 2. Move the fan farther away. You don't necessarily need to filter the air from the window closest to you. Put it in a farther window. Or go all the way and get a whole house fan that puts the fan in the attic." This might work for homeowners, but is an ineffective solution to renters like me. Our furnace/air conditioning blower is loud AF. The utility closet is next to the bedroom and it is nearly impossible to hear the TV when it is running. It is so loud that we even have to turn up the TV in the living room, around 25 feet (7m?) away and around two corners. I am CERTAIN that other renters, like myself, would like to know how to actually cancel out this droning nuisance via noise cancellation.
- IAmBroom 1y ago
  > I am CERTAIN that other renters, like myself, would like to know how to actually cancel out this droning nuisance via noise cancellation. Objecting to the proffered solutions doesn't make the unworkable one workable.

jsenn 1y ago

Is the drone of a fan harmonic? I would’ve thought it’s more like a repetition pitch so its overtones would not be harmonic and would not exhibit a missing fundamental. Agree with the broader point, just curious if there’s some interesting physics that creates a harmonic sound.

munificent 1y ago
> Is the drone of a fan harmonic? Overtones are about timbre, not harmony. The fan isn't playing a chord (well, probably not). But the tone the fan plays isn't a pure sine wave either. It will have overtones that are integer multiples of the fundamental that give it its characteristic sound. It's the same reason that a flute and saxophone can play the same note but sound different. The fundamental is the same, but the amplitudes of the overtones are different.
- jsenn 1y ago
  > It will have overtones that are integer multiples of the fundamental that give it its characteristic sound. What I’m wondering is why would the overtones go in integer multiples (I.e. be harmonic) for a fan? A flute and a saxophone have harmonic(ish) overtones because of the physics of a vibrating column of air
  - ejoso 1y ago
    So are you saying the only difference between a woodwind instrument and a fan is the column? What about a stringed instrument then? Every sound found in nature contains multiple frequency components. When these align as integer multiples of the fundamental, they are harmonics; when they do not, they are inharmonic partials. Only a pure sine wave lacks them, and such signals don’t occur naturally.
    - jsenn 1y ago
      A string fixed at both ends produces harmonic sounds because of its particular structure. In order to have a non-integer overtone the ends would have to move up and down, which by construction they can't. Similarly for wind instruments: the air stops at either end and is reflected back, and a non-integer overtone would require changing the length of the tube (or sticking holes in it to allow the pressure to go to zero at the hole, effectively creating an artificial "end" of the tube). By contrast, a freely vibrating bar (not fixed at the ends) does not have harmonic overtones. To make the bars of a xylophone, marimba, or vibraphone sound nice, you have to cut out a little "scoop" shape from the bottom of the bar to force it to vibrate such that its overtones match up with integer multiples of the fundamental frequency of the bar. As you say, most sounds in nature do not have a harmonic spectrum, so if a fan did I would find that surprising and interesting.
  - ssivark 1y ago
    > why would the overtones go in integer multiples (I.e. be harmonic) for a fan? The fan noise is from its own vibrations -- presumably driven by the motor. These vibrations will correspond to natural vibrating modes on the body of the vibrating object -- which could be the motor, or the chassis, or even possibly the fan blades. Whatever the shape, the natural modes will be naturally quantized into "harmonics". Those vibrating modes could have more nuanced spatial forms (eg. Bessel functions) but their temporal pattern would likely be sinusoid.

renox 1y ago

I wonder if it wouldn't be better to have two fans: one at a high position and one at a low position.

NoNameHaveI 1y ago

"1. Get a better, quieter fan that produces less noise to begin with. 2. Move the fan farther away. You don't necessarily need to filter the air from the window closest to you. Put it in a farther window. Or go all the way and get a whole house fan that puts the fan in the attic." This might work for homeowners, but is an ineffective solution to renters like me. Our furnace/air conditioning blower is loud AF. The utility closet is next to the bedroom and it is nearly impossible to hear the TV when it is running. It is so loud that we even have to turn up the TV in the living room, around 25 feet (7m?) away and around two corners. I am CERTAIN that other renters, like myself, would like to know how to actually cancel out this droning nuisance via noise cancellation.

IAmBroom 1y ago
> I am CERTAIN that other renters, like myself, would like to know how to actually cancel out this droning nuisance via noise cancellation. Objecting to the proffered solutions doesn't make the unworkable one workable.