Frequency ranges in music, from sub bass to air

The audible spectrum in plain English

Every sound is a mix of vibrations at different speeds, and each speed is a frequency, measured in hertz (Hz): the number of times a second the wave repeats. A slow wave at 40 Hz is a deep rumble, while a fast one at 8,000 Hz, written 8 kHz, is a hiss. Most sounds you'll mix have energy spread across thousands of frequencies at once, and the picture of how much there is at each one is called a spectrum.

Young, healthy ears hear from about 20 Hz to 20 kHz. The top end shrinks with age and after years of loud music, so by middle age most people have lost some of the highest few kilohertz. That's one reason to keep the top of a mix in check even when you can't hear it clearly yourself.

Your ears hear pitch by ratio, so each doubling of frequency sounds like the same size of step. That step is an octave. Start at 20 Hz and double ten times and you reach 20,480 Hz, which means the whole of human hearing is about ten octaves. The lowest octave, 20 to 40 Hz, is only 20 Hz wide. The highest, 10 to 20 kHz, is 10,000 Hz wide, and you still hear both as one octave. That's why every EQ screen, the one in the lab included, squeezes the high numbers together and gives each octave the same width.

The ranges on this page are names for parts of those ten octaves, so you can talk about them and find them quickly. The edges are rough: some charts end the sub at 60 Hz and some at 80 or 100 Hz, and nobody agrees exactly where the mids stop. What's in each range stays the same whichever chart you use, and that's the part to learn. The EQ lesson covers the tools you then use on them.

Reading the lab

The big screen shows the spectrum of the loop, from 20 Hz on the left to 20 kHz on the right. The pale line is the original and the teal shape follows the sound live while it plays. The display is tilted by 3 dB per octave so that pink noise, which has the same energy in every octave, reads as a flat line. A mix that looks roughly level across the screen is close to that balance.

Under the screen is a strip with the six ranges. Click one and the lab plays only that part of the sound, turned up so you hear it at a sensible level; click it again to hear everything. The lesson steps do the same with the listening band, and the Right now panel tells you how much of this loop's energy sits in the range you picked, measured from the sound itself. Pick Vocal or Drums above the screen and the same ranges sound completely different, which is a good way to learn them.

You can also drag the numbered points to boost or cut, and press A/B to compare with the original at the same loudness. To hear your own music split into ranges, load a file with + Your sound or press Record. Nothing leaves your device.

The six frequency ranges at a glance

This table uses the same boundaries as the lab. The last two columns are the words engineers use when a range is out of balance, which is often how you'll first notice a problem.

Add up the widths and they come to the full ten octaves: the sub is about 1.6 octaves, the bass about 2, the low mids exactly 1, the mids 2, the presence range about 1.6 and the air about 1.7. So the low mids, where most mud comes from, is the narrowest of the six.

Sub bass: 20 to 60 Hz

Sub bass is the bottom octave and a half of hearing. The lowest note on a piano, A0, is 27.5 Hz, the open low E on a four-string bass is 41.2 Hz, and an 808 tuned to A1 sits at 55 Hz. Below the notes there's rumble from traffic and from microphone stands getting knocked.

You feel this range as much as you hear it, and a lot of playback systems can't reproduce it. Club subwoofers are built for it and sealed in-ear headphones can go surprisingly deep, but laptop speakers, phone speakers and small studio monitors run out well before 40 Hz. A bass line that lives only down here can disappear on the devices most people listen on.

The sub also eats more headroom than any other range. A wave at 40 Hz takes 25 ms to complete one cycle, and a loud one moves a speaker cone a long way, so a little extra sub pushes the whole mix towards clipping long before it sounds loud. That's one reason engineers high-pass the parts that don't need the sub, such as vocals, guitars and pads.

Bass: 60 to 250 Hz

Most of the weight in a mix comes from this range. The body of a kick drum sits around 50 to 100 Hz depending on how it's tuned, a bass guitar's fundamentals run from 41 Hz up to about 400 Hz, and the lowest string of a guitar is 82.4 Hz. The fundamental of a speaking voice is here too: about 85 to 180 Hz for most men and 165 to 255 Hz for most women.

Too much and the mix gets boomy, a slow, heavy thickness that makes the low end hard to read. Too little and everything sounds thin. Because the kick and the bass both put most of their energy in this range, they're the pair most likely to cover each other up, which is called masking. The kick and bass lesson shows how to give each one its own space.

Untreated rooms cause trouble here as well. Low frequencies have long wavelengths, about 5.7 m at 60 Hz, and they bounce between parallel walls into peaks and dips that change from one spot in the room to the next. If the bass sounds huge at your desk and weak a metre behind it, the room is doing that, and no EQ on the track will fix it.

Low mids: 250 to 500 Hz

Middle C is 261.6 Hz, so the low mids are roughly the octave above it. Nearly every instrument has energy here: the upper harmonics of the bass, the body of guitars and keys, the low end of pads, the chest of a vocal and the shell tone of the drums. Each one sounds fine on its own. Stack them up and their low mids pile into mud, a cloudy thickness where the parts blur together.

That pile-up is the reason a cut of 2 to 4 dB somewhere around 250 to 400 Hz shows up on so many tracks in a mix. It's rarely one part's fault. A few small cuts on the parts that don't need body, such as a rhythm guitar or a pad, usually clean things up more than one big cut on the main instrument. Cut too much, though, and things start to sound hollow and cold, because this range is also where warmth comes from.

On a kick drum the boxy, cardboard tone sits around 250 to 500 Hz, and a cut there makes many kicks sound cleaner. The same cut on a vocal can take away the boxy sound of a small room.

Mids: 500 Hz to 2 kHz

The mids carry the tone that tells a trumpet from a violin playing the same note. A lot of melody lives here too: the top string of a guitar starts at 329.6 Hz, a soprano's high C is 1,047 Hz, and the harmonics of almost everything are strong in these two octaves.

Small speakers reproduce the mids much better than the low end, so this range decides a lot about how a mix sounds on a phone. A bass line with some growl around 700 Hz to 1.5 kHz stays audible there, while one that's pure sub vanishes. Too much in the mids sounds honky or nasal, and a peak around 1 kHz is what makes something sound like it's coming out of a cheap radio. Scoop the mids out and the mix sounds distant, as if the instruments have stepped back from the microphone.

Presence: 2 to 6 kHz

The highest note on a piano, C8, is 4,186 Hz. Above that, almost nothing in music is a fundamental; what you hear is harmonics and noise. The presence range holds the consonants that make words understandable, the scrape of a pick, the click of a kick drum's beater and the crack of a snare.

Your ears are most sensitive here. The ear canal is a short tube about 2.5 cm long, and its natural resonance sits around 3 kHz, so the same amount of energy sounds louder at 3 kHz than almost anywhere else. A boost of 2 dB in this range can bring a vocal forward in the mix; 6 dB can make it harsh. This is also the range that tires your ears over a long session, which is one reason a mix that sounded exciting at midnight can sound harsh the next morning.

Air: 6 to 20 kHz

The top range covers almost two octaves. Hi-hats and cymbals have most of their sizzle up here, and the s and t sounds of a voice, called sibilance, usually sit between 5 and 10 kHz. Above about 10 kHz is what engineers mean by air: a light, open quality on vocals, acoustic guitars and whole mixes that you mostly notice when it's missing.

Most music has very little energy up here, often a few percent of the total or less, which is why the waveform barely changes when you boost it. A high shelf of 1 to 3 dB from 10 or 12 kHz is the usual way to add air. Boost further and the hiss in a recording comes up with it, and the s sounds start to spit. If the s sounds are the only problem, a de-esser does a better job than a fixed EQ cut, because it only cuts while the s is happening.

A CD or a 44.1 kHz file can hold frequencies up to 22.05 kHz, half its sample rate, so it covers the whole of this range with a little to spare.

Musical notes and their frequencies

Concert pitch puts the A above middle C at 440 Hz. Every octave up doubles that and every octave down halves it, so A3 is 220 Hz, A2 is 110 Hz and A1 is 55 Hz. Each of the twelve semitones in an octave multiplies the frequency by the twelfth root of 2, about 1.059. If you know a note's MIDI number n, its frequency is 440 × 2^{(n − 69) / 12} Hz.

A note played on a real instrument is more than its fundamental. Above it sit harmonics at whole-number multiples, so an A at 110 Hz also has energy at 220, 330, 440, 550 Hz and up. The balance of those harmonics is what makes a cello and a synth playing the same A sound different, and it's why EQ at 3 kHz changes a bass guitar even though its notes are far below that.

Harmonics also explain the phone step in the lab. When the fundamental is missing, your brain works it out from the spacing of the harmonics and still hears the right pitch. A bass note at 55 Hz whose harmonics at 330, 385 and 440 Hz get through still sounds like a 55 Hz note, even on a phone that can't play anything below 300 Hz.

Equal-loudness curves and your ears

Your hearing isn't flat. In 1933 Harvey Fletcher and Wilden Munson at Bell Labs measured how loud tones at different frequencies had to be to sound equally loud. Their curves and the later ISO 226 standard both show the ear is weakest at the two ends. At a quiet listening level a 100 Hz tone needs about 20 dB more than a 1 kHz tone to sound as loud. Turn the music up and that gap shrinks.

This changes how you mix. Mix at a very low volume and you'll hear too little bass, so you'll add too much. Mix very loud and the low end and the top both seem bigger, so you'll leave them short, and the louder version will usually seem better in a quick comparison. A moderate, steady listening level, the kind you could talk over, gives you the fairest picture. The lab's A/B matches the loudness of the two versions for the same reason.

Frequency ranges on small and large speakers

A speaker has to move a lot of air to make low frequencies, so the smaller it is, the higher its low end stops. Most phone speakers give out somewhere in the low hundreds of hertz, laptop speakers do a little better, and small studio monitors with 5-inch woofers usually reach down to around 50 Hz. Club systems and good headphones go all the way to the sub.

In practice the mids and presence ranges reach every listener and the sub reaches only some of them, and a mix has to make sense either way. Check yours on the smallest speaker you own as well as on headphones. If the bass line vanishes on the small one, give it more harmonics in the mids, with EQ or a little saturation, before you reach for more sub.

How to learn the frequency ranges by ear

Knowing that the low mids are 250 to 500 Hz helps far less than knowing what they sound like. This routine teaches that in a few short sessions.

1. Start with pink noisePick Pink noise and click through the range strip under the screen. With no music to distract you, the change in pitch from one range to the next is easy to hear and easy to remember.
2. Solo each range on musicClick through the strip from Sub to Air on the full mix, then do it again on Vocal and Drums. Say out loud what each one sounds like to you, in your own words.
3. Sweep a boost through a real trackSet a bell to a Q of about 4 and a boost of 9 dB, turn your speakers down a little, and drag it slowly from left to right. Stop whenever the sound changes character and check which range you're in.
4. Match words to rangesWhen a mix sounds muddy, boomy or harsh, guess the range before you look, then check with a sweep. The table further up is the cheat sheet.
5. Test yourself with the quizUse the quiz under the lab until you can name the range most of the time without flipping A/B.
6. Listen to a mix you know wellPut on a commercial track in the same style and listen to one range at a time, the low mids on one play and the presence on the next. The reference tracks lesson covers how to do this inside your DAW.

Common mistakes with frequency ranges

Treating the chart as rules

A chart that says "cut 300 Hz on vocals" is a guess about a recording it has never heard. Use the ranges to know where to look, then let your ears decide whether anything needs changing. Plenty of vocals need nothing at 300 Hz.

Building the low end on speakers that can't play it

If your speakers stop at 60 Hz you'll keep adding sub you can't hear, and the mix will rumble on a club system. Check the sub on headphones, or watch it on an analyser, and keep it in proportion to what you can hear.

Adding air until it sounds exciting

Top-end boosts sound impressive for the first few seconds and then start to tire your ears, more so as the session goes on. Give it a few minutes away from the speakers before you decide to keep it.

Soloing every part

A guitar with its low mids cut can sound thin on its own and just right with the bass and drums playing. Judge ranges with the whole mix running, and solo only to find a problem you can already hear.

Train your ears to hear the ranges

The quiz under the lab boosts one hidden range of the loop by 9 dB: the bass at 100 Hz, the low mids at 350 Hz, the mids at 1 kHz, the presence range at 3.5 kHz or the air at 10 kHz. The screens are covered and the level is matched, so the only clue is the tone, and you can flip A/B to hear the original. Eight rounds take two or three minutes, and your best score stays in your browser so you can watch it improve.

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