Slight response deviations go unnoticed without an audible reference

Evidence

Deviations from a flat magnitude response within the audio range of 20 Hz–20 kHz change the perceived ‘colour’ or timbre of sound (Toole, 1986). However, close to the upper and lower frequency limits, the response flatness is less critical than in the mid-frequency range. The magnitude response of the loudspeaker of Figure 4.3 varies by ±5 dB in the range 80 Hz–18 kHz, which is easily noticed in direct comparison to the flat response, but without a reference most listeners cannot perceive the deviations when listening to music through the loudspeaker. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 504

Categorization

• CANDY: A ±5 dB response dip is only noticeable in direct A/B comparison, not while listening to music.