In article , ruffrecords wrote:
I have never heard it expressed in SPL but a long time ago I read that
the peak output from an orchestra is about 70 watts of acoustic power.
You should be able to work it out from that.

Yes, that sum is trivial. 70 Watts accoustic power at 10 metres over
a 1/4 sphere (assuming reflection from floor and back of the hall) is
about 113.5 dBA. The trouble is that figure of 70 Watts is very high
compared to the 7 to 10 Watts (i.e. 103 to 105 dBA at 10 metres) that
is quoted elsewhere for a large orchestra. I can find no reference to
orchestral power output that is looks verifiable.

--
John Phillips