This "rough fix" works fine for me! By using (over rather than on the ear) headphones, I am not influenced by the ambient noise level in my room (since I don't plan to wake up at 3:00 AM just to hear sound files ).

yeah, yeah. That's why I said default ringtone at default volume.

well, my point of view is, that I can compare very easily the volume of my cellphone against the computer, and it is that easy because it's an electronic sound. (to compare the noise of a kettle would be more difficult)

The idea is to have 5 or ten recorded cellphones, and if you picked the top selling models, then I must be able to find one of them easily.

I don't know anyone without cellphone, that's a huge pool to find a top selling cellphone.

Top selling cellphones does shift rather quickly, so soundfiles would need to be added every 6 months or so. On top of that MikeC would need to get hold of all the new popular brand cellphones every 6 months (sigh!).
No to mention that different brands and models are selling good in different countries, so MikeC would need to get hold of roughtly 20 new cellphones every 6 months.
I am not sure about the quality of noise level in the speaker of cellphones, but judging from the huge variation of how other parts of cellphones work I would guess that it does vary quite a lot between individual phones.

Keeping sound files for all fans that MikeC tests in the future is a much better option IMHO. This assumes that you have at least one spare fan of a type that MikeC has tested.

If you don't have any hardware available we could issue a recommendation on how to adjust volume. For instance you could use a recording of the 80mm L1A @5V in free air and adjust volume so it is just audiable. This will at least set noise level to something where the noise level of most sound files will be easy to distinguish from each other.
I hope at this setting a high speed Delta fan @12V will still not cause hearing damage, but I guess we have to test this before issuing the recommendation.

well, maybe it's not very professional the ringtone idea.

anyway, thanks for answering

I like the reference fans but i also have another suggestion.

I've seen db charts in the past but they dont seem very memorable. It would be nice to have a well illustrated chart with the corresponding sound files for common sounds such as

Threshold of Hearing ,Rustling Leaves, Whisper, Normal Conversation, Busy Street Traffic, Vacuum Cleaner, Large Orchestra, Walkman at Maximum Level, Front Rows of Rock Concert, Threshold of Pain, Military Jet Takeoff, Instant Perforation of Eardrum. The starndard 10db sounds, as long as the pictures were pretty, and the sounds roughly accurate it would make the whole reference db levels much eaiser to remember.

EDIT: forgot to include Ralph Hutter's Nieghbors barking Dog, or the average non-quiet spouse.

I've given this problem some thought and can think of another possible solution.

Record pink noise at a non-clipping volume on your setup (let's assume this is maybe 40dB @ the distance from your microphone). Using programs like Wavegain and mp3gain, we can digitally (and losslessly) amplify the noise by a fixed amount to a value that can be measured (let's say it's amplified TO 60dB).

User takes the adjusted noise sample and sets the volume so that the noise sample is at 60dB. User now knows the accurate volume that this fan noise samples are at, since the unadjusted pink noise SHOULD playback at 40dB.

I guess this is a lot more effort than I initially thought. Are there any comments or suggestions to this?

sthayashi --

That still leaves the question of who actually has access to an SLM? Maybe 2% of SPCR readers -- and probably it's not easily accessible, just that they know where they might be able to borrow one...

And does it read accurately? Most cheap SLMs are NOT calibrated, so it's going to be off anyway...

What about the dynamic linearity of the sound system? I mean OK, so let's say you've got it where it plays the 60dBA noise accurately, but does the sound system ramp down linearly? Assuming a modest PC sound system, probably not.

All in all, I think just setting the quietest Panaflo 80L 7V sound to be just barely audible at 1m is probably as good as this 60 dBA ref signal will be for most people. AND it requires no effort or running around. The dynamic linearity will be less of an issue, because you'll have set it at within 20 dBA of the loudest sound you'll want to play back.

(Assume the virtually inaudible fan sound at @1m will be around 15 dBA; anything more than 35 dBA and you don't even want to know anyway. So the desired range is only a max of 20 dBA above the calibration point. On the other hand, 60 dBA calibration tone is 45 to 25 dBA above the desired range: Much more room for dynamic non-linearity to become a factor.)

But I get back to one of my original questions for those who have read the article: Have you tried the Panaflo calibration and how do you think it works for you? I guess you will know better when there are more sound files of more fans (and other sound sources) to compare.

I don't know if they're loud enough or if their volume is the same when they're close to empty (or constant while you spray), but how about one of the compressed air dust blower cans? Anybody that deals with computers has one (or in my case, needs another). You can recommend a specific brand from some place like Best Buy. Spraying it for a few seconds is kind of a waste of the air but it's not a big deal, and easily worth all the information you would get if it works.

Could do but I haven't so far because I figured it's already data overload. Hearing it for yourself is really the best, isn't it? And the MP3 files come about as close to that as realistically possible given the fans are here and you all are out there?!

I can create 3D spectrum graphs of the sound -- freq / amplitude / time. But people have to be able to interpret the things.

It's also even more work... the reviews take long enough as it is...

yeah, the visual representation is very nice, but looking at two different but similar graphics you can't really tell which one will annoy you most.

at least that's what I heard.

Sorry about that, it was my post but i removed it at the last minute in case the images bothered anyone

I think you're right it's extra effort to make them and hearing them is the best option, but it's pretty easy to tell which one would be the most annoying, take a look at these two: nexus and panaflo. You can easily see the smoother and more consistent panaflo sound, and comparing two images side-by-side is much easier than comparing two sound files simultaneously

Anyway, I guess anyone who would like them can always generate them from the sound files themselves

maybe telephone dial tone may help you calibrate noise
or a specific type of metal like coins
and a force like g when you drop it

Dial tone is not a good way of calibrating sound level. It varies depending on provider, phone brand, signal strength, extensions, etc.

well it might be really good for cellphones
a particular brand and model of a cellphone or some popular models might be really good for calibration
because home phones vary much but cellphones more popular and same

...but cell phones don't have dial tones. Ring tones might work, but that's already been suggested.

In any case, the issue of calibration for SPCR recordings is moot since our latest recording methodology, which includes 10 seconds of ambient noise along with every recording. If you set your volume so you can just barely hear the section of ambient noise, you'll have a good idea of how it sounds in the lab.

good solution
but we can find any other solution too if we think long enough
my suggestion might be as following

boiling water
or
the sound of specific type of owen flame or some other kind of mass production kitchen household
beard shaving machines are pretty much sold and spreaded

or even better
a lighting torch for cigarettes
it is cheap and it is well sold and it all the same