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One of the more irritating factors of PCs these these is the noise it creates. Fans are giving better performance but along with that seem to be getting more audible. This is actually one of the bigger issues for small form factor PCs. In the image above you can see a DBa meter at work. Now the case fans are turned off and you are looking at default ambient sound. Despite what your brain is telling you, there is always noise in the background, from the streets and other things. The human hearing system has different sensitivities at different frequencies. This means that the perception of noise is not at all equal at every frequency. Noise with significant measured levels (in dB) at high or low frequencies will not be as annoying as it would be when its energy is concentrated in the middle frequencies. In other words, the measured noise levels in dB will not reflect the actual human perception of the loudness of the noise. That's why we measure the dBa level. A specific circuit is added to the sound level meter to correct its reading in regard to this concept. This reading is the noise level in dBA. The letter A is added to indicate the correction that was made in the measurement.
We activated the PSU, connected the fans and measured the ambient noise again with the case open. Let's have a look at the next photo.
Inside the PC there is a good portion of airflow coming from the 120mm fan, but it's a rather moderate sound level.
|
TYPICAL SOUND LEVELS | ||
|
Jet takeoff (200 feet) |
120 dBA |
|
|
Construction Site |
110 dBA |
Intolerable |
|
Shout (5 feet) |
100 dBA |
|
|
Heavy truck (50 feet) |
90 dBA |
Very noisy |
|
Urban street |
80 dBA |
|
|
Automobile interior |
70 dBA |
Noisy |
|
Normal conversation (3 feet) |
60 dBA |
|
|
Office, classroom |
50 dBA |
Moderate |
|
Living room |
40 dBA |
|
|
Bedroom at night |
30 dBA |
Quiet |
|
Broadcast studio |
20 dBA |
|
|
Rustling leaves |
10 dBA |
Barely audible |
Interestingly enough once we close the casing the noise levels rise even more. It has to do with the small mesh which can be found on the left and right side of the windows and the lack of an air intake at the front side. The air needs to go in somewhere and the design amplifies the noise level a little.
Mind you that ONLY the PSU and the 120mm fan are active at this stage.
Here's a photo of the complete install; the 120mm and 60mm fans do a reasonable job lighting this case, in a semi-twilight environment. With normal light conditions, the effect is drastically reduced, You might want to look out for cold cathode lighting in the future to get UV reactive. ;-)
