How many decibels is the sound of whispering laughter?
It's ~25 dB (SPL) from 1m away, depending on how loudly one whispers, I suppose. ~50 dB at 1m is the level of speech, and ~10 dB at 1m is the level of just regular breathing. The magnitude of sound decays with distance, so distance from the source needs to be considered.
Just remember that decibels are based on a log scale. This means that 50dB is much more than 2 times as loud as 25dB. Every increment of 3dB you increase, it's about twice as loud.
0 decibels SPL is about 10^-12 watts per square meter. 120 decibels SPL is about 1 watt per square meter. As indicated above, it is a logarithmic scale; every 10 decibels is a factor of 10 in watts/ square meter.
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