Ok, sometimes I have a little too much time on my hands and I find yet another way to waste it.
One of my neurons developed a need to know how linear (if at all) my system is at the listening position at reproducing relatively "correct" levels. The next thing I knew, some other neurons got all agitated and this measurement ensued.
I took 24 sweep measurements decrementing the beginning attenuation at my DSP by 2dB per step for 24 steps and 46dB, to see if there was anything to note.
The lowest sound pressure level is chosen around the point the signal rises out of the noise floor of the room and the measurement tool at 1kHz and above. The bass frequencies are still "noisy" at the low measurements but the higher frequencies are pretty clean.
Using 3kHz as an anchor, I see a spread of 46.0dB to 91.9dB, for a range of 45.9dB rather than the expected 46. with 1/3 octave smoothing. That result might be closer than I expected.
Looks like the air conditioning was on for a few of the lowest traces - hump at 18Hz.
1/3 smoothing
1/24 smoothing
Ambient and tool noise obvious at low level and low frequency.
For those unfamiliar with a 46dB volume attenuation range - The daily blow-by-blow of the Trump vs Clinton Celebrity Death Match is on at a fully satisfying level (86dB peak, 66dB average), then attenuate by 46dB, the result is a just barely audible something with nothing intelligible, the sound not even recognizable as voices.
One of my neurons developed a need to know how linear (if at all) my system is at the listening position at reproducing relatively "correct" levels. The next thing I knew, some other neurons got all agitated and this measurement ensued.
I took 24 sweep measurements decrementing the beginning attenuation at my DSP by 2dB per step for 24 steps and 46dB, to see if there was anything to note.
The lowest sound pressure level is chosen around the point the signal rises out of the noise floor of the room and the measurement tool at 1kHz and above. The bass frequencies are still "noisy" at the low measurements but the higher frequencies are pretty clean.
Using 3kHz as an anchor, I see a spread of 46.0dB to 91.9dB, for a range of 45.9dB rather than the expected 46. with 1/3 octave smoothing. That result might be closer than I expected.
Looks like the air conditioning was on for a few of the lowest traces - hump at 18Hz.
1/3 smoothing
1/24 smoothing
Ambient and tool noise obvious at low level and low frequency.
For those unfamiliar with a 46dB volume attenuation range - The daily blow-by-blow of the Trump vs Clinton Celebrity Death Match is on at a fully satisfying level (86dB peak, 66dB average), then attenuate by 46dB, the result is a just barely audible something with nothing intelligible, the sound not even recognizable as voices.
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