Why do strongly compressed tracks seem more attractive? (Fletcher-Munson curves)
The Fletcher-Munson curves are also known as equal-loudness contours and demonstrate the ear's tendency to hear more bass and high frequencies at higher loudness levels. Loudness circuitry in hi-fi devices is based on the ear's hearing response represented with the loudness contours. It works simply by boosting the bass and higher frequencies at quieter listening levels.
Fletcher-Munson Equal Loudness Curves
The quieter the sound level (sound pressure level in dB/SPL), the more the bass and high frequencies are boosted in order to maintain an evenly-distributed sound.
Without this comparison, the louder passage will always seem to have a little more bass and high frequency content than the quieter one and will therefore subjectively sound warmer and more brilliant, and therefore punchier.
During superficial comparisons, this effect hides the loss of transients (peaks of sound at the very beginning of percussive events). In addition, the deterioration of dynamics (which are part of artistic performance) often goes unnoticed during short A/B comparisons of short passages.
From a commercial point of view, this is a big problem: Nowadays, customers listen to and compare songs online before buying. Here, louder tracks have an advantage because every customer's sense of hearing is subject to this effect. The problem can only be solved when the most advanced technology is used for customer pre-listening for online shops. For example, Dolby Volume is a path-breaking innovation from Dolby Corporation which gives any sound source the same listening level. There are already technologies available to normalize pre-listening examples automatically.