"John Phillips" wrote in message
...

[Noting Don's correction from 19 dB to 9 dB]. May I ask if this
comparison is relevant?

Maybe not, but it is still fun to do:-)

Weighting curves are relative. AFAICS you just can't compare the absolute
audibility of A-weighted noise with ITU-R 486-weighted noise from the
same source. You can only compare weighted figures with the same type
of weighting.

Manufacturers choose the weighting which shows there amp in the best
possible light, but it is important to compare apples with apples. If all
are
using the same weighting, then there is no problem.

AFAICS, for each weighting the absolute threshold of audibility may be
rather different. What you may get from comparing 468-weighted noise
figures is a more valid comparison WRT human audibility of noise than
from comparing A-weighted noise figures.

Indeed.

Iain