mr. poopyhead wrote:
i don't mean to sound negative or anything, cause i love this site... but i have an honest question...
what is the benefit of building an anechoic chamber? nobody lives in that kind of environment so if product A is 19dBA, and B is 15dBA, won't that be completely indistinguishable to 99.999% of us due to ambient noise?
One huge difference is that Mike won't have to tip toe around at odd hours or save equipment sitting around for days or weeks at a time waiting for ambient noise conditions to be favorable.
I'm guessing every review you've ever read where mike lists his name on the by line and an ambient noise of 19 or 20 dBa is a living history of the times he was annoyed, frustrated, delayed by ambient noise that he couldn't control. Some percentage of the times he lists 18dBa might be the same but those won't stand out and we would have no way to tell from the readers side of those reviews in most cases.
I remember several reviews where he mentioned odd hours, wind, or rain as factors. Let me Google some quotes, there might be better ones but I got tired of searching so here they are:
It is important to note that the room in which the power supplies are tested is almost always very quiet, typically <20 dBA, more often <18 dBA. If it is a noisy day (due to rain, wind, or lawn mowers) we wait until it's quieter to conduct any recordings. listening tests or sound measurements.
We discuss the noise levels of PC components routinely here in the SPCR forums, but rarely does anyone talk about their ambient noise levels. I recently had the opportunity to briefly borrow a highly sensitive calibrated B&K "1613" sound level meter from the University of BC's acoustics lab.
It dates back to 1978, weighs over 10 pounds, and is completely analog in design. Yet it has a dynamic range that spans over 130 dB. Its absolutely sensitivity reaches below 0 dBA -- at one point in the midband (~1kHz) we were seeing -4 dBA in the UBC anechoic chamber. Here is a picture, next to an 80mm fan and a hard drive for reference. (warning -- 164Kb picture!)http://www.silentpcreview.com/files/ima ... &K1613.jpg
I thought it would be interesting to check the ambient noise levels around the house...
My office, which I think of as so quiet: 32 dBA at 5pm with the door and windows closed. With 2 PCs on, at sitting desk position, 34 dBA -- one of them is in a very noisy stage right now...
My wife's downstairs back office, 8pm, no one else home: 12 dBA. Very very quiet; a dog barking 4 houses away makes the meter jump to 24 dBA!
Our ambient level in the lab varies (mostly on neighborhood activities/conditions)
its technically difficult to quantitatively measure noise levels that are really close to ambient. but it's not really valid to say 'this fan is M dBA loud', by direct measurement, unless 'M' is at least something like ~6dBA above ambient (the 'delta' that the ambient level tends to add to the total measurement decreases as the measured object is louder, this ~6dBA above ambient is about where the contribution of ambient itself tends to have added only about 1dBA to the total measurement)
I considered a move to a commercial space but quickly ruled that out when I realized there is no rentable commercial space where <20 dBA ambient is possible. Until I am prepared to build an anechoic chamber, this old house will have to do, with dear Betty's understanding.