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Inside be quiet!

30.07.2019
What are decibels?

A maximum of 15,5 db(A) – that’s what how we advertise our Silent Wings 3 140mm fans. But what are decibels? What is the meaning of the letter A? And how does the number 15,5 fit in the bigger picture?

“A” stands for the frequency filter A included in the measuring tool in order to visualize acoustic signals as numbers. With this you can imitate the human sense of hearing, with a range of 20 Hertz through 20 Kilohertz. Zero db(A) equals the hearing threshold. 10 to 15 decibels is the sound of a person in deep sleep from a distance of about a meter. A conversation usually runs at 40 to 60 decibels, while a jack-hammer will register at about 100 decibels. 130 db(A) marks the average pain threshold.
Decibels are highly dependent of the distance between the source and the recipient, as the sound pressure loses intensity with distance. There is a famous formula stating an increase in about 6 db(A) when cutting the distance between the microphone and the source in half. Regarding to that formula many think that an increase in six decibels means a doubling in in volume. Which is wrong. What actually doubles is the intensity of the acoustic pressure. The accepted rule of thumb amongst acousticians is that a tenfold increase in acoustic pressure causes a doubling in subjective volume – which is what happens at ten decibels.


If you put ten Silent Wings 3 fans next to each other you increase the acoustic intensity tenfold while the volume only gets doubled. Which means that the fan noise in itself isn’t the main problem with silence-focused PCs – it’s actually other sources of noise, such as graphics cards, air flow or the electrical whine of coils or capacitors.