Is there a updated SPL for the recommandated fans?

[netmask254]

Previously SPCR's ambient noise level is 19dB when testing those fans, but recently they improves it to a much smaller value. Then the problem is, the previous data is no longer usable for reference, especially for low speed recording.

My interest is: Is there an updated SPL for those best rated fans? I have a SFLEX 12cm@600rpm & a Notuca S12 12cm@800rpm. I'd like to know some more accurate SPL to plan the overall quietness

[jessekopelman]

Previously SPCR's ambient noise level is 19dB when testing those fans, but recently they improves it to a much smaller value. Then the problem is, the previous data is no longer usable for reference, especially for low speed recording.

My interest is: Is there an updated SPL for those best rated fans? I have a SFLEX 12cm@600rpm & a Notuca S12 12cm@800rpm. I'd like to know some more accurate SPL to plan the overall quietness

If you look at the newest few heatsink reviews/roundups, you will see that they have updated values for the reference Nexus Real Silent 120mm. That fan is 11-12dBA @600RPM and 12-13dBA at 800RPM. When they were tested head to head, the Real Silent was ~1dB quieter than the S12 with both at 800RPM. For additional reference, the quietest HDD tested by SPCR are in the 12-13dBA range at idle.

[netmask254]

Thanks a lot! That's exactly what I need.

I always thought there is no much difference on SPL for those best fans. One fan is enough to me

[netmask254]

Now I have another another question, what's the perceivable noise level in a quiet room? I know it is difficult to answer, but wish to get a general answer or a range.

I'm planning my quiet PC upgrade, but don't know whether the combined noise of all components is low enough
CPU fan: 12cm@600rpm
Exhaust fan: 12cm@800rpm
GPU: AC S1 Passive or with a very low speed (<500rpm) 12cm fan
Harddisk: WB GreenPower
PSU: 12cm@<500rpm in low load speed. Enermax Mod82+ is a great choice (Nexus 430 Value is not available in local market), but I'm also seeking for some other alternatives more affordable.

Previously I thought SPL no larger than 20dB should be almost not perceivable generally, from the impression of reading multiple reviews from SPCR. According to the latest review, I guess the SPL of 1200rpm fan should be around 17~18dB. But I remember exactly that I can hear the noise of my SFLEX-E 12cm@1200rpm (since the first day it arrives) from 1 meter away in my bedroom in night. BTW, I don't think my bedroom is as quiet as SPCR's previous test room, it is not far from a street actually.

Nexus 120mm fan measurements:
Voltage Noise RPM
12V 16dBA@1m 1100 RPM
9V 13dBA@1m 890 RPM
7V 12dBA@1m 720 RPM
5V 11dBA@1m 530 RPM

[jessekopelman]

I think the SPL in even a very quiet room is actually around 20dBA. The problem is that your ears can hear things that are well below the ambient noise floor. I'd say even 10dBA below the noise floor is hardly a problem (until you get ambients < 10dBA, as 0dBA is the limit for typical hearing). Score 1 for evolution, but that's a point against building an inaudible PC with moving parts . . . What that means is that as we get into lower SPL level, the actual qualities of the noise (things like tone and variability) become very important. This is one of the reasons MikeC prefers to use constant speed fans -- it is easier to pick out the change in fan noise than either of noise states themselves (assuming they are both low). This is also why even though there are many 120mm fans that are down around 13dBA at 600-800RPM, some are still "quieter" than others. What makes the Nexus the reference is not just it's low SPL but also the was it actually sounds.

[netmask254]

Thanks very much, I can understand it now.

Though in theory there is the so called sound masking effect (http://en.wikipedia.org/wiki/Auditory_masking), different sounds have different characters (e.g. different spectrum and tones). Unless it becomes somewhat "white" like noise (flat spectrum), our ears are still able to act as a filter to recognize it.

[jessekopelman]

Thanks very much, I can understand it now.

Though in theory there is the so called sound masking effect (http://en.wikipedia.org/wiki/Auditory_masking), different sounds have different characters (e.g. different spectrum and tones). Unless it becomes somewhat "white" like noise (flat spectrum), our ears are still able to act as a filter to recognize it.

Yes, I think that is a pretty good way to put it. To be nerdy about it, I'd point out that it is not just about filtering but also antenna theory. Inside your ear you've got all these tiny hairs that function like sonic antennae. They are connected to nerves and the network can be thought of as a phased array antenna, capable of incredible gain. Unfortunately, it is not all under our conscious control. Sometimes your brain decides to apply all that gain to resolving sounds that you'd rather not hear.

[Hypernova]

Thanks very much, I can understand it now.

Though in theory there is the so called sound masking effect (http://en.wikipedia.org/wiki/Auditory_masking), different sounds have different characters (e.g. different spectrum and tones). Unless it becomes somewhat "white" like noise (flat spectrum), our ears are still able to act as a filter to recognize it.

Yes, I think that is a pretty good way to put it. To be nerdy about it, I'd point out that it is not just about filtering but also antenna theory. Inside your ear you've got all these tiny hairs that function like sonic antennae. They are connected to nerves and the network can be thought of as a phased array antenna, capable of incredible gain. Unfortunately, it is not all under our conscious control. Sometimes your brain decides to apply all that gain to resolving sounds that you'd rather not hear.

Animals have evolved to automatically focus on the unknown, seek patterns where there are none etc as it aids in survival in the wild. Unfortunately all these data processing occurs automatically. In the future if we have engineered humans it would be nice to have conscience control over these functions.

[jessekopelman]

Animals have evolved to automatically focus on the unknown, seek patterns where there are none etc as it aids in survival in the wild. Unfortunately all these data processing occurs automatically. In the future if we have engineered humans it would be nice to have conscience control over these functions.

I wonder what could be accomplished with enough training and self-discipline. Kind of like the Mentat from Dune. Well, they did have drugs too, so not just training and self-discipline.

[Hypernova]

Animals have evolved to automatically focus on the unknown, seek patterns where there are none etc as it aids in survival in the wild. Unfortunately all these data processing occurs automatically. In the future if we have engineered humans it would be nice to have conscience control over these functions.

I wonder what could be accomplished with enough training and self-discipline. Kind of like the Mentat from Dune. Well, they did have drugs too, so not just training and self-discipline.

I doubt it would be much, else it would be more wide spread. You can train to have high tolerance for pain but there's no way to shut it down.

Damn it would be nice if we can have tunable equalizers for our ears. Or shut down nerves that are sending pain signals at will.

[jessekopelman]

I wonder what could be accomplished with enough training and self-discipline. Kind of like the Mentat from Dune. Well, they did have drugs too, so not just training and self-discipline.

I doubt it would be much, else it would be more wide spread. You can train to have high tolerance for pain but there's no way to shut it down.

Damn it would be nice if we can have tunable equalizers for our ears. Or shut down nerves that are sending pain signals at will.

There are Yogis and martial arts practitioners would would disagree with you (on the pain issue). Lack of being widespread is no indication of anything. No matter how great the gain, few people are willing to devote their entire life seriously training -- not to mention that for some things you have to start in infancy.