The steady-state room curve should tilt downward while the direct sound stays flat

Evidence

A very logical answer is that the house curve should be flat and, consequently, not emphasize any particular frequency. This conclusion unfortunately does not appear to hold true in practice. It has been the consistent experience of this author, and many other experimenters, that a flat house curve is subjectively too bright, and should be rolled off by as much as 10 dB at 10 kHz. … The amount of the attenuation is about right: 10 dB, which if distributed over a 20 Hz to 10 kHz range (9 octaves) yields a slope of −1.1 dB/octave, the slope of the target curve tolerance in Figure 11.8b. However, the question is: at what frequency should the rolloff begin? The weight of the evidence points to a relatively linear tilt starting at a low frequency. The notion that a frequency response should be flat is, as Schulein said, “logical,” but it is the direct sound that should be flat, not the steady-state room curve. — , Toole, Floyd E - Sound reproduction-…, 1320

Categorization

• XREF: Connects to the chapter’s recurring theme linking loudspeaker directivity, room curves, and listener preference — ties directly to the flat-direct-sound findings at location 1292. — connects to: Spatially static resonant modes cause sound level to vary across a room — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1953; Steady-state frequency response is the reliable indicator of audible room resonances — Toole, Floyd E, Sound reproduction- the acoustics and…, 956; Flat-response speakers unavoidably produce a bass-heavy steady-state room sound — , Toole, Floyd E - Sound reproduction-…, 1216
• ADDENDUM: Parallel to the theme in my trees-as-infrastructure essay where the visible ‘surface’ structure (flat response) masks the deeper functional architecture — here the flat direct sound, not the room curve, is what matters.

Broader Connections

• Flat-response speakers unavoidably produce a bass-heavy steady-state room sound #expands (0.85) — , Toole, Floyd E - Sound reproduction-…, 1216
• Spatially static resonant modes cause sound level to vary across a room #complicates (0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1953
• Steady-state frequency response is the reliable indicator of audible room resonances #qualifies (0.70) — Toole, Floyd E, Sound reproduction- the acoustics and…, 956