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## Main Question or Discussion Point

Hello,

I have a question that I've been struggling to find an answer to / understand. Probably because my understanding of physics is quite limited :)

Before I ask the question, these are the things I take as facts, so please correct me if something is wrong:

1. A speaker in half space (close to a wall), measures at 6 dB SPL higher than the same speaker in free field - because pressure doubles (True for the omnidirectional part of the spectrum). Neumann LINK

2. Two speakers, relatively close to each other, playing the same signal, measure at 6 dB SPL higher than each speaker individually - again, because pressure doubles. This is not true for uncorrelated signals. Sengpiel audio LINK

3. If I have one speaker, and I want to achieve +6 dB SPL, I need to quadruple the power (twice the power = +3 dB), this means using 4 times more electricity.

CONFUSION: But if we have two speakers side-by-side, as in one of the examples above, we get the same 6 dB boost by using only twice the electrical power.

To further clarify. The inverse-square-law explains that for a doubling of sound pressure we need 4 times the intensity. With intensity being "power per unit of area", and power being the rate of energy "usage" - this makes me conclude that having two speakers on simultaneously - uses twice the electrical power, but "creates" 4 times sound intensity, which, to me, seems paradoxical.

I'm sure I'm either misunderstanding something, or conflating some terms, but I hope that I've at least made clear what I'm misunderstanding. Any clarification would be much appreciated.

I have a question that I've been struggling to find an answer to / understand. Probably because my understanding of physics is quite limited :)

Before I ask the question, these are the things I take as facts, so please correct me if something is wrong:

1. A speaker in half space (close to a wall), measures at 6 dB SPL higher than the same speaker in free field - because pressure doubles (True for the omnidirectional part of the spectrum). Neumann LINK

2. Two speakers, relatively close to each other, playing the same signal, measure at 6 dB SPL higher than each speaker individually - again, because pressure doubles. This is not true for uncorrelated signals. Sengpiel audio LINK

3. If I have one speaker, and I want to achieve +6 dB SPL, I need to quadruple the power (twice the power = +3 dB), this means using 4 times more electricity.

CONFUSION: But if we have two speakers side-by-side, as in one of the examples above, we get the same 6 dB boost by using only twice the electrical power.

To further clarify. The inverse-square-law explains that for a doubling of sound pressure we need 4 times the intensity. With intensity being "power per unit of area", and power being the rate of energy "usage" - this makes me conclude that having two speakers on simultaneously - uses twice the electrical power, but "creates" 4 times sound intensity, which, to me, seems paradoxical.

I'm sure I'm either misunderstanding something, or conflating some terms, but I hope that I've at least made clear what I'm misunderstanding. Any clarification would be much appreciated.