Muddy, boxy, harsh: mix problems you can hear

By Dan Murtagh · Updated 27 September 2026

Short answer: most mix problems are too much of one range of frequencies. Muddy is too much in the low mids, roughly 200 to 400 Hz. Boxy sits around 300 to 600 Hz, honky around 1 kHz, harsh around 2 to 4 kHz, and sibilance, hard S sounds, around 5 to 9 kHz. Dull is too little up top, where the air is. The exact spot moves with the instrument and the song, so learn what each one sounds like, then find it by ear.

The ranges below are where each problem usually lives. Engineers draw the lines in slightly different places, and the spot moves with the instrument, so treat them as where to start looking. For where each instrument sits, see the EQ frequency chart on danmurtagh.com.

Muddy: the low mids

Roughly 200 to 400 Hz. A muddy mix sounds thick and woolly. Notes blur into each other, words lose their edges, and the mix gets bigger without getting clearer. It happens because almost every instrument has energy here, so it piles up: guitars, keys, the upper part of the bass, the body of the kick, the chest of a voice, and reverb on all of them.

The fix is rarely one big cut on the mix. Find the part adding the most, cut it there, and high-pass the parts that don’t need low end. Cut where it’s piling up, not on every track, or the mix goes thin.

Boomy: the low end

Below about 200 Hz. Boomy is one bass note jumping out, a kick that swells, a low end that feels heavy and slow. Rooms and headphones both play tricks down here, so check boom on more than one system before you cut it. Mixing on headphones has a check for it.

Boxy

Around 300 to 600 Hz. Boxy sounds hollow, like the sound is coming out of a cardboard box. Drums recorded in small rooms and instruments miked close often have it. It usually sits in a narrower band than mud, so a narrower cut often sorts it.

Honky

Around 700 Hz to 1.5 kHz. Nasal, like a voice down a phone line. Vocals, guitars, horns and piano all honk when there’s too much here.

Harsh

Around 2 to 4 kHz. Hard and tiring to listen to: the mix pokes at you, and you want to turn it down. Ears are very sensitive in this range, so a few dB too much is enough. Guitars, vocals and cymbals are the usual suspects. Judge harshness at a moderate level: turned up loud, everything sounds harsher.

Sibilance: the S sounds

Around 5 to 9 kHz. Sibilance is S, T and SH sounds that spit or hiss louder than the rest of the voice. Where it sits depends on the singer, the mic and the words, so find it with a narrow boost and a sweep. A bright EQ move on a vocal makes it worse. The usual fix is a de-esser, which turns that range down only when an S hits, rather than a static EQ cut that dulls every word.

Dull, and the air band

Air is roughly 10 kHz and up. It’s less a note than a sense of openness: breath, the shimmer of cymbals, the room. A dull mix has too little up there, and sounds like it’s under a blanket. A gentle high shelf opens it up; too much and you’re turning up hiss and S sounds. Shelving EQ has a demo.

How to find a problem by ear

1. Name it first. Muddy, boxy, honky, harsh, sibilant, dull. The name tells you where to look.
2. Find the instrument. Listen for which part the problem is in, with the mix playing. Solo only to confirm.
3. Boost and sweep. On that part, set a fairly narrow boost and sweep it slowly through the range. The problem jumps out when you’re on it.
4. Turn the boost into a cut, of the smallest amount that fixes it. Then flip it off and on, at the same level, with the mix playing.

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