We have a few threads about running 'quiet' systems recently so I thought it about time to roll out a useful scale so that peeps have some idea what the nominal dBA level quoted for a fan or PSU etc is really going to sound like.
First thing to remember is that for our purposes sound is measured in dBA which is a logarithmic scale, not a linear scale referring to an individual's perception of the oudness of a sound. This means that a 7-8dBA increase is about double the perceived sound level and a reduction in 7-8dBA will approximately half the oerceived sound level. If the figures quoted are dB (sound pressure in air) then a 6dB increase will double the sound pressure, a 6dB decrease will halve the sound pressure. Sound pressure as you will have gathered does not relate directly to our perception of loudness, hence the dBA scale used. But they are close enough to be of use when comparing companents with either dB or dBA ratings.
dBA Levels
Just audible is 10 dBA
Soft whisper at 15 feet is 30 dBA
A quiet room is about 28dBA
A noisy drive measures about 36-38 dBA
A quiet office is about 40 dBA
Air conditioner, normal speech, 60 dBA
Noisy restaurant, freeway traffic, noisy office, 70 dBA
Hearing protection recommended at 80 dBA
Lawn mower on grass is 85 dBA
Heavy truck in traffic measures 90 dBA
Rock concert is 110 dBA
Car horn at 3 ft, maximal vocal effort results in 120 dBA
Thunderclap is 130 dBA
Stryker's farts are 138 dBA
Jet aircraft taking off from a carrier deck is 140 dBA
Hope this 'scale' helps you when you are wondering exactly how loud a 'quiet' component really is!
TL. 8)
Component Examples:
Delta Fan 80mm:
Airflow 80CFM
Noise 52.5dBA
Zalman Fan 80mm:
Airflow : 20.6-36.5cfm
Noise : 20-34.2dBA
Antec Fan 80mm:
Airflow 34 CFM
Noise 30 dBA (at average rpm)
Thermaltake 80mm Fan:
Noise : 30dBA
Airflow: 37cfm
Thermaltake Smartfan 80mm:
Airflow 20.55-75.7 CFM
Noise 17 dB - 48 dB
As you can see, even from such a small selection of basic 80mm case fans, there is a huge variation in both the amount of air that can be moved and also the operating noise. Air volumes range from 20-80 CFM, but sound level goes from 17dBA to a massive 52 dBA. That means that the loudest fan will sound many times louder than the quietest!
TL. 8)
Sometime I do wonder why I bother trying to make my mundane life more interesting by reading up on some things to post for you peeps. 31 people viewed the thread and not a single one of them read it :P Not even Stryker :lol:
Sheesh :roll:
TL. 8)
QuotedBA Levels
Thunderclap is 130 dBA
Stryker's farts are 138 dBA
Jet aircraft taking off from a carrier deck is 140 dBA
lol.....I think people took it as a fundamental point that Strykers farts are 138dB
A little bird once told me that to raise 1 dB of noise you have to double the amount of sound pressure (some logarithmic jive going on there)….thus a change of only 1 dB is a significant jump……..as posted above
But the frequency also has an impact as humans can only hear a small range of noise….and measurements are generally taken over all frequencies
As with Strykers farts I heard that they filtered the sound to only measure high and low frequency….the low frequency came in at 0.003 dB where as the high end burst ear tissue with its “dog whistle†like 138dB……. 0.003 second burst which people cant hear only smell
This in turn means that most measurements are corrupt and the best way to do it is with 2 paper cups and a piece of string (By placing one paper cup over the fan and the other cup in a sound proof room then listen)
QuoteStryker's farts are 138 dBA
TL. 8)
Oi!!!
just noticed that, I'll have you know my farts are at least 150dBA, esp with follow-through.
QuoteQuoteStryker's farts are 138 dBA
TL. 8)
Oi!!!
just noticed that, I'll have you know my farts are at least 150dBA, esp with follow-through.
Surely a follow-through has a damping effect 8O
u never heard of explosive shits?
then again with what I hear about ur TANGO at dmw LAN 1 I think everyone has heard them.
QuoteQuoteQuoteStryker's farts are 138 dBA
TL. 8)
Oi!!!
just noticed that, I'll have you know my farts are at least 150dBA, esp with follow-through.
Surely a follow-through has a damping effect 8O
Damping effect 8O 8O I don;t care WHAT effect it has - just get me outta here fast! 8O
TL. 8)
Just to correct claims of "6db" and "1db" above:
For what it's worth, it is in fact a 3db increase that is a doubling of sound pressure. This is not the same as a doubling in perceived _loudness_ of course.
All db is logarithmic. The dbA scale is simply weighted to try and account for the fact that the human ear doesn't hear all frequencies at the same efficiency - as you'll probably know, to make bass sound as "loud" as higher frequencies, you generally need a thumpingly large speaker/amp. dbA (and the like) adjust the values based on the frequencies in the sound to indicate the likely perceived level of sound for legislative purposes. Or something like that...
Yours pedantically,
tugs.
(tealeaf's younger brother, wot went to university to study acoustics.
and even turned up to about 1 in 5 lectures, too. Ok, one in ten then.
Oh, who am I trying to kid...)
:oops:
/me struggles to remember which university physics department gave me the 6db figure as doubling :oops: I remember reading some of the stuff I researched and finding a debate about it and someone well qualified and professorish gave the mathematical argument to prove 6, so I figured he was the one who was right. :( Never trust a nerd, they'll turn on you the first chance they get 8O
Oh, whilst we're at it little bro', come play some PCS god damn you :D
TL. 8)
(tugs' big brother, wot went to university to study accounting, turned up to about 3 in 5 lectures, acquired 2 out of 3 available credit cards, duped 1 out of 1 bank managers into giving me a handsome overdraft facility, used 1.5 out of 1 overdraft facility, and still found time to DJ on 3 of 7 nights, be a bouncer on 2 of 7 nights and be drunk on 7 of 7 nights. Sheesh, and Sheepeh thinks he's is the only one who gets drunk...... :D )
Quote Sheesh, and Sheepeh thinks he's is the only one who gets drunk...... :D )
No he just tells us about it frequently. The rest of us cabbage in silence!
i dont tell u abaout it all the time ts just that u lot always bring it up
Quotei dont tell u abaout it all the time ts just that u lot always bring it up
Is this time for a 'vomit' joke? Nah, you're right, I won't. :D
TL. 8)