What is Coloration?
Every material resonates when struck or activated. This is how different materials, or for that matter musical instruments, make their identifiable sounds or tones. Speakers should be neutral, having no identifiable sound of their own, but speakers are prone to resonances that color or alter the sound — these are unwanted and must be eliminated. In the same way the tint in a pair of sunglasses colors what you see, unwanted resonances color what you hear. They impose themselves on vocals and instrumental sounds being reproduced (see chart). Coloration compromises fidelity and hampers imaging by blending sounds together. Speakers with low coloration are timbrally accurate — they faithfully represent the timbre or distinctive character of every sound it reproduce.
Common colorations that must be controlled to ensure greater reproduction accuracy:
Shrill or Dull Overall sound is too sharp (shrill) or too muffled (dull).
Harsh Resonances in the 2 kHz to 8 kHz region make high frequencies sound grating.
Nasal Speak while pinching your nose. Resonance problems in the 1 kHz to 2 kHz range result in a "nasal-like" sound.
"Ahh" Sounding Cup your hands and place them around
Hollow Form a cylinder with one hand. Place it to your mouth and speak. A speaker that sounds like this has resonance problems in the 200 Hz to 600 Hz range.
"Boxy" These speakers are plagued by uncontrolled enclosure resonances in the 90 Hz to 200 Hz region. Upper bass lacks clarity and definition.
"Boomy" In a "boomy" speaker, sound in the 60 Hz to 100 Hz range is overblown. Bass is "bloated" and poorly defined.