Sidney

I have; I did not know he uses his old kitchen. But, I have a hard time to accept the value. As I said I use to manufacturer audiometers and hearing aids.

http://som.flinders.edu.au/FUSA/BME/...iometerCal.htm

I will say his value is off; unless he can show me the calibration; or use a second calibrated meter. A setup like this! http://www.silentpcreview.com/Sectio...artid-211.html

http://www.digital-recordings.com/audiocd/radio.html

Generator of 94 dBA at 1000hz (identical to mine).

I worked here from 1975 to 1985 - http://www.beltone.com/

I am not saying he is right or wrong; I merely want to learn how he constructed his kitchen + the equipment ...... in getting 16 dBA reading. That will really be nice and making a great contribution to the hardware review sites; as we all can learn from him.
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Normal breathing is about 10dBA.

http://www.freehearingtest.com/noiselimits.shtml

Normal hearing test - not everyone can hear 10 dB; and 15 to 24 dB you are consider okay. Red color = Right ear

http://www.advancedhearing.com/page/652772

It is imperative to understand a 16dBA room is very rare. Anything that is so rare deserves our attention.
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If the sound room a converted kitchen has 16 dBA noise level (rare to my knowledge); a fanless system registered 20dBA 1 meter away, tell me how many other equipment such as ceiling light, any electronics and electrical nearby that contribute to the 16dBA base line which could possibly be lowered.

So, assuming all the reported dBA readings are valid (assume), the validation of the 16 dBA ambient or white noise is required plus the way the level can be maintained during the recording prceedings.

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lazyman

Opteron 165 (2) @2.85 1.42 vcore AMD Stock HSF + Chill Vent II

Sidney

During hearing test, an Auro-Dome (a specially made heardphone) is used to hear the tones, 10 dB is not easy to hear by most people today at certain frequency.

I gave two audiometers to my nephew a couple of years ago in hoping he got some interest in science and medical field. I will find out in the morning if he has not destroyed them. If they are still in okay shape, I may be able to run some tests using them as sound generators at several specific frequencies.

Perhaps, it is about time I go visit some of my old audiologist friends and get some of the professional opinions on this very sensitive (in hearing) issue happening in the home Personal Computer arena in a rather load noise

Edit - auro-dome should be aural-dome.

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lazyman

Opteron 165 (2) @2.85 1.42 vcore AMD Stock HSF + Chill Vent II

mikec

Hi Lazyman,

Chances are pretty good that the 16 dBA reading mentioned here does not refer to the noise level in the kitchen. It is the lowest SPL measured in an adjacent 20'x10' room that is wall-to-wall carpet & underlay over concrete slab, with heavy drapes across one short wall... at about 2am on a still winter eve. There are no noise sources in the room other than the device being measured, all other PCs in the building measure <22 dBA@1m, and the fridge & freezer in the house are fairly quiet, located some 45 ft away.

Stomache gurgling audible only to me causes a deflection in the needle of the SLM 2-3 feet away. A light sigh is easily picked up.

The meter had not been calibrated for a few months, but it wasn't out -- after cailbration showed the same result. Admittedly, it is the residual noise level of the electronics in the meter anyway.

There's been lots of disbelief about these readings in the past, and I suppose there will be in future. What I can say is that they are A weighted, and subjectively, it sounds pretty close to the anechoic chamber at the Univ of BC where the A-weighted readings are 16~18 dBA, typically.

I think it helps that the room is on the ground floor, on a concrete floor, and in the wee hours of the night, the neighborhood is really dead; the nearest highway is at least 1.5km away.

Typically, the minimum background noise during the day is around 20 dBA.

The only noise that comes from the PC reviewed was the hard drive -- and it was definitely audible, even encased as it was. Normally, we record the noise and present it as a high quality MP3, but this was too low to be worthwhile; most people's audio playback gear would make more residual noise anyway.

One of the interesting issues we come across at SPCR is the intrusiveness of noise as you approach inaudibility. Typically, the quieter the PC is, the less white/pink noise it produces. What's left -- often at miniscule, just barely audible levels that you have to work hard to hear -- is a more pure tone. We're talking about something like the 120Hz tone of a 7200rpm HDD down at around 18-20 dBA@1m. Or some single overtone of this freq. in the 1khz range. You'd think this is much better than 25 dBA@1m... but it is not always so. If the latter is broadband, smooth and unchanging, it can be more benign and easier to ignore than the pure tone at super low level. Somehow, the tone can become more audible and annoying over time rather than less so.

Hence the discussion of the HDD 1-2khz tone in the review.

jmke

hey Mikec, thank you for taking the time to register and answer in our forums; we been following SPCR for years now and truly love the site and the time you devote to the project.

the only reason we're being a bit "repetitive" about the dBA measurements is because of the ambient noise in most places being >30dBA easily without anything running in the room; even in a deserted basement.

you are absolutely correct about the low level tones being able to annoy you more than a slightly louder noise source; that's why I like your inclusion of sound samples, as the dBA measurement alone doesn't quite tell the whole story.

however whenever you go below the <40dBA noise level you're going to the extreme enthusiast area -- with the system you reviewed from EndPCNoise I'm sure the loudest noise is now the keyboard and mouse clicks

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Sidney

Hi mikec,

Pleasure to read your reply in detail regarding some of my disbelieves. I too live in a place with min of 30 meters from the next building (house). The lower level is ~3 ft below ground, concrete floor and carpeted + another layer of underlayment, highway is min. 10 miles away, a residential with 1/2 to 1 acre lot size. Being in the mid-west snow belt, homes here are better insulated than those in the sunbelt.

Like jmke indicated above that most quiet home has a white noise level of >30dBA which is kind of in the low side for my take; 35 to 38 dBA may be more in the ball park for most. The lowest noise level in my house is 37 dBA.

What puzzles me the most is that fact that people are getting after something that is close to unmeasurable with high price sound meter. With an Aural-Dome on my hear, the audiologist says "pay attention to the tone, a very short burst this time at 15 dB'.

"The tree sounds when the wind blows", "If a tree falls over in a forest and there is nobody there to hear it - is there still a noise?"

The PC noise will not be heard if the noise level is below the normal houeshold white noise; noise is a natural phenomenon. Most people will fail a pure tone hearing test at 10 - 20 dB and their hearing can be considered normal

Noise masking and white noise answer some of the unpleasure tone one does not want to hear. I do feel living in a sound chamber or a place with 16 dBA will only make a normal person insane.

Provided I truly have a 16 dBA ambient noise level, my PC is the top of the line in emitting no more than 20 dBA; the noise from the clock next to me, the sound of the keyboard from every stroke I make, noise from my stomach will sound like an orchestra. I have had worked in a sound chamber at ~16- 20dBA, I did not feel well after about one hour of work. It is not a healthy situation for most normal people.

Having said all that, I am more amazed that your test environment matches with the noise level of a sound chamber in University of BC where they must have spent/invested quite a lot.

Neverthless, I truly appreciate your participation on the very topic.

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lazyman

Opteron 165 (2) @2.85 1.42 vcore AMD Stock HSF + Chill Vent II

Sidney

http://64.233.179.104/search?q=cache...=clnk&cd=7</a>

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http://reviews.cnet.com/4520-3118_7-6323963-1.html

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lazyman

Opteron 165 (2) @2.85 1.42 vcore AMD Stock HSF + Chill Vent II

mikec

Thanks for the welcome.

re -- the need for some noise: Yes, it's true. However there are few computers so quiet as to not contribute anything to the overall acoustic. Mostly, PC silencers don't want another source of artificial noise; there is enough of it everywhere.

I experienced a gotach recently: Got into a HDTV & subscribed to sattelite digital TV for HD, along with PVR/box. Earlier I had discovered the Sonly 42" LCD rear-projection TV has at least one fan in

mikec

--hmmm -- can't edit the half finished post accidentally submitted above.... ah well, to go on:

...one fan in it, and it caused the ambient in that room to go from 22 dBA up to around 30 dBA -- at the seated position some 6-7' away. This I could not tolerate! Against my principles and so on

So I swapped up, spending another $800 or so on a 40" LCD TV that doesn't have a fan. That was before the satellite TV gear was installed.

Now I discover that the PVR/satellite tuner has a HDD that runs constantly. It's hardmounted to the chassis with a fan bolted directly beneath it, and there is a fat void warranty sticker inside on the HDD/fan subassembly.

Noise? Oh yeah. Up >30 dBA, with the vibration of the HDD/casing causing the whole hardwood floor to resonate.

Got me. :grr:

It's under control sitting mechanically decoupled on some open foam, inside a cabinet, with the shelf lined w/ acoustic foam. Not a permanent solution... but I have come up with some ideas for a vibration / noise damped media center cabinet.

I know, I know, who cares when the TV / movie is on? But it's not always on, and unless you actually unplug the PVR / tuner box from the wall, that noise is always there. Surely, I am not the only one who notices. This has to be a serious annoyance for most people.

Sidney

New homes in the last 15 years are big on "great room" having faimily room connected to the kitchen with high ceiling (~20 feet); patio door (or French door). This creates a area excessive of 1,000 sq.ft. of open space (kind of). There are enough noises to arrive a higher white noise level with frequencies masking each other. Yes, my brother's 50" Toshiba LCD has two small fans on the back also.

I am just a regular Joe, with 37dBA ambient noise. I am pretty happy with a PC noise of < 40 dBA 18" away in any room; at 36" I won't notice the noise.

It just happened that we at [M] have had more than a few conversations about dBA meter and sound. It is because our Editor in Chief was kind enough to pay for part of the cost in equiping most of us a digital meter.

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Whenever one pays attention to everything (highly unlikely), some of them will bother the hell out of us. We are unaware of most of the advertsing printed on newspaper, TV and whenever we go. Yet, they are everywhere. If you must pay close attention to the noises around, I am sure you will hear it however slight the noise may be. Often times, one will simply learn to egnore it. I hate the humming sound from florescent light (the Ballast) only when I pay special attention to it. Otherwise, it is masked by other noises.

Image how much sound does a flying mosquito make? Not hell a lot, yet it bothers the hell out of me. For a couple times a year, I really don't give a damn. Thank God my hearing is still okay

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lazyman

Opteron 165 (2) @2.85 1.42 vcore AMD Stock HSF + Chill Vent II

mikec

That's interesting. At least they are trying. PCWorld contracted me to do a review on a couple fanless systems in 2004 -- http://www.pcworld.com/news/article/0,aid,115370,00.asp

This ultra-short piece got a bit bigger for SPCR -- here's the specifics on the Hush fanless: http://www.silentpcreview.com/article151-page4.html