Why Do My Vocals Sound Boxy or Muddy?

Does it sound like your vocal recordings are muffled or slushy? Almost like you had a cardboard box on your head while singing them? Then you may be suffering from muddy tone. It’s a common phrase to hear in the world of music production.

Thankfully, it’s also an issue that is fixable. In this quick guide, I’ll explain what “muddy” or “boxy” tone usually means and how to correct your vocal track that suffers from it.

Why Do My Vocals Sound Boxy or Muddy?

Vocals usually get described as boxy or muddy because of too much going on in the lows or low-mids (anywhere up to 500 Hz). These frequency ranges are full of ambient noise and clashing bass information which causes a muffled or dampened tone in the mix.

For vocals, you really do not want any frequencies below 100 Hz—that area contains a lot of ugly room resonance. Likewise, any audio in these low ranges will most likely compete against the bass guitar and kick drum…and it’s not going to sound pretty.

Husky vocals (common among contralto or baritone singers) may need to cut out frequencies up to 250 Hz to remove the boxy tone.

How to Fix Boxy or Muddy Vocals

So how do we remove the cardboard box sound from your voice? Here are a few common ways to remove murky, muddy tones (both before you start recording and while mixing):

  1. Prevent proximity effect
  2. High-pass out the low end
  3. Boost the highs

Prevent Proximity Effect

The proximity effect is when you sing too close to a condenser microphone and it causes bass frequencies to build up, leading to an artificial boost in your voice’s low end. This can help to beef up a thin or fragile voice. But too much of anything can be bad.

The proximity effect can easily cause muffling and boomy tone in an audio recording.

If you have a low voice, or thin tone is not an issue, then keep your distance from the microphone when recording.

Exactly how far should you be from the microphone? Well, that depends on your voice, the mic that you’re using, and what tone you want for the song. Here are rules of thumb, though.

How Far Should You Be From a Condenser Mic?

For most condenser microphones, a good starting point is to position yourself 6 inches away from the mic face, with your mouth facing the front mesh. Start 12 inches away if you know your voice is deep or you’ll be singing loudly/aggressively. These distances should prevent proximity effect from muddying up the mix.

The most popular budget condenser microphones are usually large diaphragm cardioid condensers, and that’s what I’m using for the basis of these recommendations. Ribbon microphones tend to be even more susceptible to proximity effect.

If your voice sounds thin at that initial distance, try moving an inch or two closer but monitor for low-end frequency build-up. For very soft vocal takes, get as close as you can without ruining the take with mouth sounds (excessive wet noises from your lips opening and closing).

Here’s one more pro tip on singer placement: if you want/need to get in close to your condenser mic but the bass response is an issue, then position yourself off-angle from the microphone. Don’t sing directly into it, but rather sing past it by standing a few degrees off axis from the front mesh.

Singing from the side of the mic will negate the proximity effect and naturally reduce sibilance…even without a pop filter.

How Far Should You Be From a Dynamic Mic?

A good starting point is to stand/sit 2-6 inches away from a dynamic microphone. That’s because dynamic microphones are less sensitive than condensers, so you can practically eat the thing if needs be. Dynamic microphones do not suffer from proximity effect and usually have built-in pop filters.

High-Pass Filter

If you already recorded some vocals, you can still reduce low-end mud by equalizing. The most common method for cutting low-end on an audio track is to simply apply a high-pass filter with an EQ plugin.

A high-pass filter is a roll-off curve that cuts the volume of frequencies below it’s cutoff point. All frequencies above that point are unaffected, but everything below that point will get gradually diminished the farther they get below the cutoff.

Start with a cutoff frequency around 150 Hz. Listen to your vocals while in the full mix and adjust the cutoff point up or down based on how much mud you’re hearing.

Boost the Highs

Lastly, you can further combat murky low-end in your vocals by turning up the high end. This technique is best applied in conjunction with a high-pass filter. Increasing the volume of the mid-highs while reducing the volume of the low-mids should clean out your vocal resonance.

I personally start this boost process by adding a bell curve around 2 kHz to my EQ and turning up the gain by 5-6 dBs. Then I’ll sweep through the mid-high range during playback and look for a frequency zone that pulls my voice forward in the mix.

If that alone doesn’t help, I will then add a high shelf around 10 kHz to the EQ (only 2-3 dBs of gain, though).

As with any mixing process, the numbers I’m mentioning are mere guidelines and the exact frequencies to adjust will depend on your vocal range, tone, and the song at hand.


Muddy vocals can quickly ruin an otherwise good track and cause discouragement. But they don’t have to. Take steps during the recording and mixing processes to shape your vocal frequencies for a better mix.

I hope you found this guide helpful. If so, then here are a few more articles to consider:

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