Sound or no sound creates industries

Others/Editorials by SidneyWong @ 2005-03-24

Our hearing is a subjective measure of sound; or is it an objective measure of sound level? I think it is loud. No, I disagree; it is not as loud as I thought. When a Plant Manager said it is not loud enough to wear hearing protection ear-plugs, he may well be cited by OSHA for violations. Both way, we pay money to create and we pay to eliminate, sound. Let´s take a look at how much noise FANs inside a PC make.

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Sound Level :

The last time I took a hearing test was two years ago give or take a few months. At my age, the result was promising. I still could hear pretty well, although not as good as a 19-year old. I was in the hearing aid industry for 10 years and have some knowledge about sound, where people pay a lot of money to hear "sound". In recent years, I kind of involve with some PC stuffs, and notice an interesting trend about noise emitting from PC, where people are eager to pay money to get rid of sound.

When I say trend, I mean for sometimes PC enthusiasts did not seem to care about the loud noise generated by the "fame" delta and tornado fans; for awhile "the hall of fame" entitlement required ownership of such fans. It lasted for about a year or two before larger fan 90 and 120 mm began taking roots in favor of slower turning speed in order to reduce noise level. Users are attracted to water-cooling for the same reason - lower noise.
Fan controllers become hot seller in taming the delta and tornado allowing users the ability to slow down the screamers.

Since my hearing is considered normal (two years ago), I hope my hearing ability has not decelerated. I like to share with you what I have collected and gathered some information about sound level from FANS before I get to the age when a 6,000-RPM Delta fan is the only sound I can hear. A word from OSHA provides detail information on sound level requirements. An old Chinese saying "The tree sounds when the wind blows". It means more than the obvious, however taken the face value; it may just mean what it says. Now, I like to know "when the wind blows the Tree remains silent" is possible.

  • Does larger fan size reduce noise level?
  • Do dBA specifications provided by manufacturers correspond to real world situation?
  • Is water cooling the answer to quiet computing?

  • The Referee :
    Not the best, with 94 dBA calibration built-in, enough to do what I intented to do here.

    Madshrimps (c)

    The Setup :

    Madshrimps (c)Madshrimps (c)

    To build a certifiable sound room for this exercise would be out of my reach. Instead, I cleaned up my work bench and have a "clean" tablecloth over it to have a setup that is close to what we are likely to experience in our everyday environment. After all, we don't live in a sound test chamber where sound waves don't get bounced around. Here is the condition/environment of the test area.

  • Sound saturation ~37.4 dBA
  • Sound meter CEM DT-8850 35-100 dBA Low, 100-130 dBA High
  • Power Supply without fan connected (running fan less)
  • Air movement – calm with no wind speed
  • Fan tested is suspended by 2.5” foam
  • Microphone is ~ 4” from the test fan
  • All windows in the room are closed during the test

    There is an air-vent located about 10 feet from the test bench; the air-vent is shut closed during the test. The sound meter fluctuates +/- 0.5 dBA; reading is taken after 30 seconds of continuous measurement; the lowest number is recorded.

    Of course, A Sound Test Chamber will be something that meets all acoustic standards in the industry. A similar sound room and a bit smaller I used back in the old days, you could hear your own heartbeats after a few minutes sitting down.

    Madshrimps (c)
    Source: NASA

    The Players :

    Madshrimps (c)

    A bunch of fans after my Pre-Spring clean up - all are used for a few hours at best for testing, some are relatively new and none are more than 1 year old.
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    Comment from Sidney @ 2007/12/08
    Should have done this earlier. Let you judge what is silent, quiet or dead silence relative to dBA numbers you have read.
    Base level of my room noise is 37.2 to 37.8 dBA.