The midrange is where the fundamental frequencies of most instruments and the human voice live. Mixing the midrange correctly is the most critical skill — if the midrange is balanced, the mix will translate to any playback system. This is why legendary mixing engineer Bob Clearmountain said: 'Mix the midrange, and everything else takes care of itself.'
The presence range (2–5 kHz) within the midrange is where vocal clarity and instrument definition live. Too much in this range sounds harsh and fatiguing; too little sounds distant and unclear. Most commercial mixes have a carefully controlled presence range that sounds detailed without hurting the ears.