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dBA comparison

S

Swufabuda

Junior Member
I'm not really up on dBA comparisons with noise levels I might know. Could someone tell me about how load is 19.66 dBA. I want to replace my case fans and am looking for best air flow to noise ratio I can find. Or should I say most air flow with the least amount of noise.. Thanks
 
That would be very, very quiet, but odds are that if you're working from manufacturer's specs they are completely unrelated to the noise the fan really does generate.
 
Originally posted by: Bobthelost
That would be very, very quiet, but odds are that if you're working from manufacturer's specs they are completely unrelated to the noise the fan really does generate.
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If it's coming from the actual manufacture of the fan (Adda, Panaflo, Delta) then it's probably pretty accurate. If on the other hand it's coming from a third party marketing division (SilenX, or Thermaltake) then there is a good chance its way off.
 
Originally posted by: Operandi
If it's coming from the actual manufacture of the fan (Adda, Panaflo, Delta) then it's probably pretty accurate.
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You can meassure it so and so. In a case with or without resonance dampening, outside a case with a vibration free suspension etc. The latter is what they usually do and thus makes the figure totally useless for people like us.

 
don't forget the distance they measure it from, and also the direction their mics are pointed, and the ambient noise while measuring.

Best you looked for 3rd party measurements =p
 
dBA is not that good at judging sound. It only measures sound intensity.

I've seen numerous situations where the higher dBA fan sounded much more pleasant then the lower dBA fan. There can be some obnoxious motor and bearing noises that aren't indicated in the dBA spec.
 
20 dBA is below ambient room noise in most homes. Only measurements taken in the same space, everything located the same in the space, and with the same equipment are really comparable. So review sites like SPCR are the places to look. a 3dB change is about the minimum that can be discerned by most people while a 10 dBA change is subjectively twice the sound level.

.bh.
 
Originally posted by: CalvinHobbes
19.66 db is pretty damn quiet (IMO)
http://www.lhh.org/noise/decibel.htm
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I'm having trouble with the benchmarks on that site. It lists 110dBa as being equivalent to someone shouting in your ear, and then a "symphony concert" at 110 as well. Umm... I don't know if the authors have ever had someone shout in their ear before, but I have and it puts you on the ground fast with pain and rage seething through your entire head. That would be one hell of a concerto...

I'm curious about dBa comparisons myself, and I'm having to learn to benchmark and compare by the different fans that I try out.
 
as someone above me stated, anything sub 20db is extremely quiet. Even my ACF12's which are rated at 24db's i cant hear them more then 2 feet away. Anyhow, theres a lot of factors when determining how quiet something is. If you have something called constructive interference, sound waves traveling at the same phase, (IE, 2 identical fans next to each other) they will add to the db raiting. So two fans at 19db will produce combine more then 19, somewhere near or close to double *IN THEORY* but will most likely total to about 25+ and not actually 38db. So dont think adding 5 fans which are 19db will give your system an overall of 19db because that just wont happen.
 
Originally posted by: aigomorla
as someone above me stated, anything sub 20db is extremely quiet. Even my ACF12's which are rated at 24db's i cant hear them more then 2 feet away. Anyhow, theres a lot of factors when determining how quiet something is. If you have something called constructive interference, sound waves traveling at the same phase, (IE, 2 identical fans next to each other) they will add to the db raiting. So two fans at 19db will produce combine more then 19, somewhere near or close to double *IN THEORY* but will most likely total to about 25+ and not actually 38db. So dont think adding 5 fans which are 19db will give your system an overall of 19db because that just wont happen.
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Two identical sources nets you a 3dBA gain; so two 19dBA fans will measure in at 22dBA. It works for everything, not just fans and pretty much across the entire scale.

Originally posted by: Zepper
20 dBA is below ambient room noise in most homes. Only measurements taken in the same space, everything located the same in the space, and with the same equipment are really comparable. So review sites like SPCR are the places to look. a 3dB change is about the minimum that can be discerned by most people while a 10 dBA change is subjectively twice the sound level.

.bh.
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SPCR has in a few tests measured below 20dBA, but with a pro level SPL meter. For all practical purposes 20dBA is silent, and difficult to accurately measure. To get any lower you would have to measure in an anechoic chamber.

Originally posted by: Henny
dBA is not that good at judging sound. It only measures sound intensity.

I've seen numerous situations where the higher dBA fan sounded much more pleasant then the lower dBA fan. There can be some obnoxious motor and bearing noises that aren't indicated in the dBA spec.
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Good point, the ear is more sensitive to certain frequencies. So in theory a fan that measures 25dBA could be perceived louder then a 28dBA fan depending on the motor and or bearing noise.

Still the dBA rating is a pretty good indication of noise and a starting point at least.
 
Symphony orchestra would probably be 110dB measured at one meter while the shout in the ear is 100dB at an inch or two. Sound operates on the inverse square law: twice the distance - 1/4th the sound level. But in a closed symphony hall, the acoustics should enhance the sound so even the ones in the back can hear. The inverse square law operates in open air or in an otherwise anechoic space.

.bh.
 
Originally posted by: imhungry
Hmm..

Is the S-Flex really that quiet?

It's quietest fan is ~8db and look at how much air it pushes..
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No, the S-Flex numbers are a complete fabrication. The fans are quiet by all accounts, but not that quiet.
 
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