The prequel to the ‘A Quiet Place’ saga got me thinking.
spoiler alert!
There is a scene in which many humans march towards a safety point. Each individual human would have been relatively quiet, but because there are a lot of them (potentially hundreds), they end up being, as a whole, loud enough to alert the monsters so they get all killed.
This would suggest that many sources of noise which are near to each other and generate more or less the same amount of noise end up adding up so that the end result in dB is more or less the sum of the individual dB levels.
But then again, it’s fiction.
Back to reality, I work in a room full of different servers which have also very different levels of noise. I have noticed that from my standpoint, the noise of the quietest server seems to disappear whenever the loudest is running, so it kind of does blow my mind how our perception of noise works…
There’s a lot of things going with sound, but in general sound1 + sound2 is louder. You may not always perceive that, and if one of them is significantly louder, it’s not a significant difference. Active noise cancelling uses sound to make other sounds disappear, but this is just a trick, the pressure is still there (it’s why prolonged use of active noise cancelling can be bad for you).
When it comes to decibels, dB, it’s a logarithmic unit so adding them isn’t straightforward. You need to do logarithmic addition, so 5dB + 5dB = 8dB, and 90dB + 90dB = 93dB, but 70dB + 90dB = 90dB.
Curious about info on the effects of long term ANC exposure. I’m guessing what’s happening is fairly consistent pressure, right? Hence the “underwater effect” on some devices. Is it any different than being in a higher pressure environment? Or does it work like noise does?