Regions of the audible spectrum
Human hearing spans roughly 20 Hz to 20 kHz, though the upper limit declines with age. The range is conventionally divided into bands: sub-bass (about 20 to 60 Hz), bass (60 to 250 Hz), low mids (250 to 500 Hz), mids (500 Hz to 2 kHz), high mids or presence (2 to 6 kHz), and treble or air (6 to 20 kHz). The fundamental frequencies of most musical notes sit in the bass and midrange, while the higher bands carry harmonics, articulation, and a sense of openness.
Where instruments and sensitivity sit
Different sources occupy characteristic regions: a kick drum and bass guitar live in sub-bass and bass, vocals and most instruments center in the mids, and cymbals and string detail extend into the treble. Human hearing is most sensitive between roughly 2 and 5 kHz, the band that carries speech intelligibility, a sensitivity captured by equal-loudness contours (the Fletcher-Munson curves). This is why even small boosts in the presence region are easily noticed.