Uncorrelated sound waves sum by power, not by amplitude.
Evidence
On the other hand, if the sound waves are uncorrelated, then they do not add algebraically, like correlated waves; instead, we must add the powers of the individual waves together. As stated earlier, the power in a waveform is proportional to the square of the pressure levels, so in order to sum the powers of the waves, we must square the pressure amplitudes before adding them together. If we want the result as a pressure, then we must take the square root of the result. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 244
On the other hand, if the sound waves are uncorrelated then they do not add algebraically, like correlated waves; instead we must add the powers of the individual waves together. As stated earlier, the power in a waveform is proportional to the square of the pressure levels, so in order to sum the powers of the waves we must square the pressure amplitudes before adding them together. If we want the result as a pressure then we must take the square root of the result. — David Howard, Jamie Angus, coustics and Psychoacoustics, 237
Categorization
- DEFINE: Clarifies the key technical distinction between correlated and uncorrelated wave summation.
- corroborated: 4 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 244; David Howard, Jamie Angus, coustics and Psychoacoustics, 237
- XREF: connects to: Mutual resonance between sources boosts combined power beyond their sum; Even identical instruments playing in unison produce uncorrelated waveforms.; Correlated sound sources add pressures while uncorrelated ones add energy (+10 more)
Broader Connections
- Sound power and intensity levels are unaffected by source correlation, unlike pressure level
#expands(0.95) - Correlated waves interfere with each other while uncorrelated sources do not
#expands(0.92)