Multiple correlated sound sources

In rare (or contrived) cases, if the sound sources emit waveforms that are strongly correlated, there will be interference.

Solution 2: When two waves of the same frequency and amplitude $A$ reach the same point, they may interfere destructively or constructively resulting in a pressure amplitude range of

• 0 (complete destructive interference) to
• $2A$ (complete constructive interference).

In the case of a doubling of pressure, there's an increase of $20\log(2) = 6$    dB. Thus doubling the sound source can result in a sound level change of 0-6 dB (depending on interference) for correlated sounds.