Calculation Results
About This Calculator
Calculate sound pressure level (SPL dB) drop over distance using the acoustic inverse square law (-6 dB per doubling of distance), speaker sensitivity, and amplifier wattage.
Frequently Asked Questions
What is the inverse square law for sound pressure level?
In a free acoustic field without reflective boundaries, sound pressure level drops by exactly 6 decibels (6 dB) every time distance from the point source speaker is doubled (e.g. 100 dB at 1m becomes 94 dB at 2m, 88 dB at 4m).
How much amplifier power is needed to double perceived loudness?
In human psychoacoustics, a 10 dB increase is perceived as approximately twice as loud, requiring a 10-fold increase in amplifier wattage (e.g., jumping from 10 Watts to 100 Watts). Doubling power (3 dB gain) produces only a modest, barely noticeable volume increase.
What does speaker sensitivity (dB SPL @ 1W/1m) measure?
Sensitivity measures how efficiently a loudspeaker converts electrical power into acoustic sound pressure. An efficient 96 dB speaker requires only one-quarter the amplifier wattage of an 87 dB speaker to produce the identical volume.
What is the OSHA maximum safe sound exposure threshold?
OSHA occupational noise standards establish 85 dBA as the action level where hearing conservation is required, permitting 8 hours of exposure at 90 dBA, 4 hours at 95 dBA, and only 15 minutes at 115 dBA.