Spatial averaging and in-situ power measurement reveal identical boundary effects

Evidence

Figure 13.6 shows a comparison of the two methods in the same room, one the result of making frequency response measurements at nine very different listening locations, and the other the result of a measurement of the sound power radiated by the loudspeaker. They are remarkably similar and, if any amount of spectral smoothing were incorporated, they would be even closer than shown. Obviously, this means that an in-room measurement of radiated sound power can identify the adjacent-boundary problems, and so can a spatial average of in-room measurements. Both methods allow us to separate out the adjacent-boundary problems, but the solution applies everywhere throughout the volume of the room, which is unlikely to be what is needed for any particular listening location. The effects of room resonances are added to this, so there will be seat-to-seat variations. If the equalization is performed at a single listening location, it will obviously be correct for that seat, and it will be a combination of adjacent boundary and room resonance problems. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1473

Categorization

• XREF: Power radiation vs. spatial average convergence also appears in diffuse-field and room absorption measurement theory.
• QUESTION: Worth chasing: how does spatial averaging differ in cost and reliability from in-situ power measurement across varying room sizes?