In article ,
John Laird wrote:
It's not exactly clear what "10 times" means... Almost certainly not
that you could have 10 of them on at the same time and only making the
same amount of noise as 1 of the louder variety. Fwiw (and there are
some sound gurus lurking around here), I believe the average ear can
only discern a change of about 3dB (maybe 2). 10dB is perceived as an
approximate doubling in volume, iirc.

I'm fairly certain the origin of the decibel (or bel, of which it is a
tenth) is that it is the minimum change in level that the average ear can
determine in its most sensitive range. 3dB might well be a more practical
amount, though, as an average across the audible spectrum.

Nevertheless, the quieter machine will be noticeably quieter, but
perhaps not throughout its full cycle. They probably use some averaging
algorithm to quote results.

I'd hope they're quoting the peak level, and it should be 'A' weighted to
take into account the varying sensitivity of the ear to different
frequencies.

--
*What do little birdies see when they get knocked unconscious? *

Dave Plowman London SW 12
RIP Acorn