How far does PSU have to be from ones ear to not hear it?

belkincp · Post by **belkincp** » Tue Feb 06, 2007 4:23 am

Lets say the psu makes 22 decibels, and everything else in the system is dead silent.

belkincp · Post by **belkincp** » Tue Feb 06, 2007 5:39 am

anyone

Post by **Ralf Hutter** » Tue Feb 06, 2007 6:31 am

Wasn't it Abe Lincoln who answered "long enough to reach the ground" when asked how long a man's legs should be?

So, in that vein, my answer to your question is "far enough away so you can't hear it". That distance will vary depending on the PSU, environmental factors and the quality of your own hearing.

jaganath · Post by **jaganath** » Tue Feb 06, 2007 8:30 am

http://www.illbruck-sonex.com/faq_glossary.php

Inverse Square Law

-Sound levels fall off with distance traveled. Sound level drops off 6 dB from the source point for every doubling of distance.

So let's say by 2 feet the noise level has dropped 6dB, that is 16dB, most people's ambient noise is above that, so it should be effectively inaudible at 2 feet.

spookmineer · Post by **spookmineer** » Tue Feb 06, 2007 2:36 pm

jaganath wrote:http://www.illbruck-sonex.com/faq_glossary.php

Inverse Square Law

-Sound levels fall off with distance traveled. Sound level drops off 6 dB from the source point for every doubling of distance.
So let's say by 2 feet the noise level has dropped 6dB, that is 16dB, most people's ambient noise is above that, so it should be effectively inaudible at 2 feet.

That is in free field. In a living room, it will be less then 6 dB because of walls and floor (reverberation).

jaganath · Post by **jaganath** » Tue Feb 06, 2007 3:59 pm

spookmineer wrote:
jaganath wrote:http://www.illbruck-sonex.com/faq_glossary.php

Inverse Square Law

-Sound levels fall off with distance traveled. Sound level drops off 6 dB from the source point for every doubling of distance.
So let's say by 2 feet the noise level has dropped 6dB, that is 16dB, most people's ambient noise is above that, so it should be effectively inaudible at 2 feet.
That is in free field. In a living room, it will be less then 6 dB because of walls and floor (reverberation).

With a proper steel case the attenuation provided by the case alone should take it below ambient. So even if it's only 4dB reduction at 2 feet it should be inaudible.

bonestonne · Post by **bonestonne** » Tue Feb 06, 2007 6:51 pm

i don't want to start any controversy, but since 22dB is actually dependant fully on noise vibrations, if the system is blocked by something, it'll be close to inaudible, no matter how far or close...like under a desk vs on the desk...so i could even be at your feet, but if something is causing the sound to bounce off somewhere else, you wouldn't hear it...2 feet is fine, but it wont matter if theres nothing stopping it, the sound will just be quiet-er than it would next to you.

Devonavar · Post by **Devonavar** » Wed Feb 07, 2007 4:37 pm

If you're wanting to use the results of this poll to judge SPCR's noise results, it would have been simpler to ask that question directly.

It's not possible to give a straightforward answer, for reasons pointed here already:

- ambient noise will make a huge difference to audibility at this level.
- mounting a PSU in a case will have a damping effect.
- the angle of listening affects how loud a given PSU sounds.
- it depends on what you count as "inaudible".

SPCR's PSU measurements are typically done with the SLM directly behind the fan, which is close to the loudest position. The ambient noise level is typically ~19 dBA.

A PSU that measures 22 dBA@1m is typically audible from anywhere in the test room (approximately 15' square), but not outside it. It is quiet enough that it only takes a few seconds for me to tune it out when I am not actively listening for it.

Keep in mind that, with the noise level so close to ambient, the noise quality matters as much or more than the volume. A pure tone at 22 dBA@1m is much easier to hear and is far more irritating than an white noise "whoosh" that measures 22 dBA@1m. I would estimate that a 22 dBA pure tone would probably disappear at ~30', while a whoosh sould probably disappear at <10'.

ckolivas · Post by **ckolivas** » Wed Feb 07, 2007 8:52 pm

I've got SPCR inspired hardware where the loudest component measures 21dB and is very respected on these forums and reviews. However my pc is in a very quiet environment 10 feet from me and the difference between pc on and off is incredible. Having used computers for 24 years now I can say I sorely miss the days when no computer had any sort of fan in them.

jaganath · Post by **jaganath** » Thu Feb 08, 2007 2:25 am

ckolivas wrote:I've got SPCR inspired hardware where the loudest component measures 21dB and is very respected on these forums and reviews. However my pc is in a very quiet environment 10 feet from me and the difference between pc on and off is incredible. Having used computers for 24 years now I can say I sorely miss the days when no computer had any sort of fan in them.

Have you tried going fanless? There's never been a better time for it (unless you need massive computing power).

ckolivas · Post by **ckolivas** » Thu Feb 08, 2007 4:03 am

Alas moonlighting as a linux kernel developer and doing lots of video reencoding means the sort of computing power I need is greater than that of affordable passive computing, and the hard drive is actually the loudest component; going 2.5" would improve that by a little, but the performance drop does matter to me.

See viewtopic.php?p=316453

How far does PSU have to be from ones ear to not hear it?

How far should a psu be from ones ear to not hear its 22 decibels?

How far does PSU have to be from ones ear to not hear it?

vote???