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Audibility thresholds of amp and DAC measurements

j_j

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Hi @j_j
Apparently the quietest anechoic chamber is at Microsoft and it was measured at -20 dB(A) SPL. Do you know how to correctly interpret and compare those numbers?
(I guess maybe A-weighting can account for some of the difference)

They estimate the EXCESS NOISE by subtracting the "atmospheric noise". Yeah, that's kind of hinky. The atmospheric noise will be there at 1 atmosphere pressure. Always.

I'm quite aware of how the room is spec'ed and built. There's no magic, it's a way to make impressive numbers. Weighting would have some effects, but they can calculate the actual noise floor, and then they measure how much above the noise floor the room is, and subtract the thermal noise floor to find the excess noise.

Also, of course, if you measure in any one ERB, you'll get a smaller number. That would also be, well, true but misleading.
 

DonH56

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<elided>
Again, tonal vs. narrow-band-noise is not very different, but yes, you can, at your ear canal resonance, get into small negative SPL's, but only if you're young and your organ of corti is un-blasted-to-bits.
Well, crud, I lose on both counts...
 

NTK

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This may be a little off topic. I had been looking for this Auditory Demonstration CD by the Institute for Perception Research (IPO) at Eindhoven University of Technology (TU/e), Northern Illinois University, supported by the Acoustical Society of America.
I finally found it at the TU/e site. Free download!
 

Hayabusa

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So is narrow-frequency noise. You do understand that the 6dB is white noise, across 20-20K, yes? So the energy in any 1 ERB is much smaller.

I would suggest you go watch through my "hearing tutorial" at www.aes.org/sections/pnw in the "meeting recaps" area. This may help you to realize you just compared an apple to a grapefruit.
nothing wrong with that, in this case we ARE comparing apples and grapefruits. Wideband noise and tonal information. A 6dB SPL white noise level suggest for others maybe that that's the absolute lower limit, but its not. That's why I made my statement. Maybe someone else found it useful.
 
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