Resonance-free response and flat direct sound define timbral neutrality

Evidence

The most important feature of these measurements is that there is no evidence of strong resonances. These would show up as repeated bumps in the family of curves because sound from resonant activity tends to radiate in all directions, whereas acoustical interference bumps and dips change with angle and are averaged out in the spatial averaged curves below the on-axis curve. This characteristic combined with a flat direct sound is the prime indicator of a timbrally neutral loudspeaker. The shape or tilt of the off-axis curves is less important than their smoothness in this respect. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1933

Categorization

• DEFINE: Distinguishes resonances (angle-independent) from interference dips (angle-dependent) — key physical mechanism for identifying resonant loudspeakers from polar measurements.
• corroborated: 2 independent passages support this claim — Toole, Floyd E, Sound reproduction- the acoustics and…, 1933
• XREF: connects to: Timbral neutrality drives 69.5 percent of sound-quality preference; Noncoincident resonances yield smoother speaker response than spherical shapes; Reflections increase sensitivity to low and mid-Q resonances in reproduced sound (+1 more)

Broader Connections

• Noncoincident resonances yield smoother speaker response than spherical shapes #expands (0.85)
• Trained listeners perceive flat spectra from loudspeakers whose on-axis response is flat #exemplifies (0.80)
• Reflections increase sensitivity to low and mid-Q resonances in reproduced sound #complicates (0.75)