-2
$\begingroup$

I notice that when I switch on my fan inside my room, the room becomes soundproof to a great extent to the outside noises. The greater is the speed of the fan, the greater is the soundproofing.

When the fan is switched off, the soundproofing is almost gone. Even little sounds from outside can come in and disturb me.

In fact, now I use my fan to soundproof my room while working.

What is the reason behind this phenomenon? Why switching on the fan inside my room, makes my room soundproof to a great extent?

Improve this question
$\endgroup$
5
  • 6
    $\begingroup$ Does the fan make a constant humming noise? Possibly, what you are experiencing is a trick of the mind, an illusion, where the added constant fan noise is considered as a constant background noise by the brain. This background noise might then "drown out" other noises, because your brain tunes your hearing to the constant background noise. This is just a guess, though, without knowing any details about the setup, effect or activity of the fan $\endgroup$
    – Steeven
    Commented Apr 10, 2020 at 12:00
  • 2
    $\begingroup$ Exactly, it's the fan's noise which might be overwhelming external noise, which perhaps you might not have noticed consciously $\endgroup$
    – Orion 73
    Commented Apr 10, 2020 at 12:05
  • $\begingroup$ We know that sound travels in the medium of air, so when the air is constantly moving randomly, then could that affect the transmission of sound? $\endgroup$
    – Devansh Mittal
    Commented Apr 10, 2020 at 12:07
  • $\begingroup$ See en.wikipedia.org/wiki/White_noise A fan doesn't produce pure white noise, but it's fairly similar, apart from the extra energy in the motor frequency (& its low order harmonics) $\endgroup$
    – PM 2Ring
    Commented Apr 10, 2020 at 12:15
  • $\begingroup$ Related post by the OP: physics.stackexchange.com/q/542860 $\endgroup$
    – user258881
    Commented Apr 10, 2020 at 13:06

1 Answer 1

Reset to default
4
$\begingroup$

this is an effect called masking, in which the random noise of the fan raises the overall noise floor in your room. For your ears to perceive anything else above that that noise floor, it has to be about +3dB "above" it, which means it must be twice as powerful.

In this way, you can make bothersome noise (music, voices, car horns, etc.) inaudible to your ears by playing a sound that is not bothersome at the same time, and adjusting its volume until the bothersome noise can no longer be perceived.

This technique is used all the time in large open offices to help make conversations in one cubicle not bothersome to the occupants of other cubicles nearby. In this case, random "white noise" is played continuously over the building's speaker system whenever people are in the office.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.