Audio
SPL at distance
How loud will a speaker be at the listener position?
Inverse square law — every doubling of distance from a point source drops the SPL by 6 dB. Use the 1-m sensitivity from the speaker datasheet (the spec sheet number that's usually labeled "SPL @ 1W @ 1m" or similar).
inputs
Distance unit
predicted SPL at listener
75.9dB SPL
inverse-square loss: −18.1 dB at 8.00 m
Real rooms add reverb gain and obstruction loss. This number is the free-field upper bound — what you'd measure outdoors on a windless day from a single point source. Use it as a sanity check, not a spec.
Need this math wired into a real system? We do that for a living.
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