Gregory O'Drobinak wrote:
>
> I find it rather peculiar that folks are worried about a 2 dB gain error =
due to
> complications using a single 1 KHz tone for doing the calibration as Raim=
und
> suggested and yet are not worried about the huge calibration error due to=
using
> the band-limited pink noise (BLPN) as a stimulus!
Hi Greg,
Thanks for your support...
There is another strong argument against the BLPN calibration method:
Given that the emitted sound level of the 1 kHz test signal generator was a=
lready known (measured in a quiet anechoic chamber), then this (soft) pure-=
tone reference signal can be easily distinguished from any ambient noise th=
at might already be present in the field at the time of the calibration. A =
narrow-band analysis filter tuned to 1 kHz (or a FFT spectrum) would be abl=
e to reject that broad-band ambient noise, which would otherwise lead to er=
rors.
A broad-band noise reference signal however cannot safely be distiguished f=
rom the ambient noise. For this reason, the BLPN signal had to be much loud=
er (lets say 10 to 20dB) than the ambient noise. Otherwise, the level of th=
e test signal would be overestimated.
Regards,
Raimund
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