Articles · Published 10 October 2026

How to use an equalizer on Android: a practical guide to the frequency bands

An equalizer (EQ) is a set of filters that make some frequencies louder or quieter. It sounds simple, yet most people open an EQ app, push every slider up in a “smile” shape, and end up with music that is louder, boomier and harsher at the same time. This guide explains what the main frequency regions do, how to listen for them, and how to make changes that actually help.

What the numbers mean

Each slider on a graphic equalizer controls a band centred on one frequency, measured in hertz (Hz). Low numbers are deep sounds, high numbers are bright ones. Human hearing covers roughly 20 Hz to 20 kHz, and each doubling of frequency is one octave, so the bands on a 10-band EQ are usually spaced one octave apart (31, 62, 125, 250, 500 Hz, 1, 2, 4, 8, 16 kHz). A 25-band EQ splits the range into narrower slices, which lets you fix a problem without disturbing its neighbours.

The level of each band is expressed in decibels (dB). +6 dB roughly doubles the signal amplitude in that band; −6 dB halves it. Android’s own Equalizer effect works the same way: an app asks the system how many bands the phone offers, what their centre frequencies are, and what range of gain is allowed, and the answers differ from phone to phone.

A tour of the bands

The descriptions below are rules of thumb used by sound engineers, not exact boundaries. Every recording, headphone and speaker is different, so always trust what you hear.

Around 60 Hz – weight and rumble

This is the region of kick-drum thump, bass-guitar fundamentals and the “feel” of electronic music. Headphones can reproduce it well; most phone speakers cannot (see our article on why phone speakers sound thin). A small boost here adds body on headphones. Too much makes everything sound bloated and eats the loudness budget, because low frequencies carry a lot of energy.

Around 250 Hz – warmth or mud

The lower midrange is where voices and instruments get their body. A little extra sounds warm; too much sounds muddy or “boxy”, as if the music is playing inside a cardboard box. If a track feels congested, a small cut around 200–300 Hz often clears it up better than boosting the treble.

Around 1 kHz – the core of the midrange

Much of the musical information lives here: guitars, piano, the body of the voice. Boosting 1 kHz makes sound more forward but can quickly turn “nasal” or honky. Cutting it slightly makes sound feel more distant and relaxed.

Around 4 kHz – presence and clarity

Our ears are particularly sensitive in the 2–5 kHz region; the equal-loudness contours in ISO 226 show that tones here are heard at lower sound pressure than tones at the frequency extremes. Consonants that make speech intelligible sit around here too. A gentle lift helps dialogue and podcasts; a large boost becomes harsh and tiring very fast.

Around 10 kHz – air and sparkle

Cymbals, breath and the “space” around a recording. A small boost makes music feel open; too much exaggerates hiss and sibilance (the sharp “s” sounds, usually a little lower, around 5–8 kHz).

A simple method that works

Start flat. Reset every band to 0 dB and listen to a song you know well, at your normal volume.
Name the problem first. “Too boomy”, “voices hard to follow”, “harsh”, “thin”. Each maps to a region above.
Cut before you boost. Removing a few dB where there is too much often sounds more natural than adding where there is too little, and it never causes clipping.
Make small moves. 2–4 dB is a big change. If you need +10 dB somewhere, the source or the speaker probably cannot deliver it.
Compare at equal loudness. A louder version almost always sounds “better” at first. Turn the overall level down after boosting, then compare.
Save it per device. A setting for headphones will rarely suit the phone speaker or a car.

Common mistakes

The big smile curve. Boosting the lows and highs a lot and leaving the mids makes music exciting for a minute and fatiguing after ten. It also hides vocals.
Boosting bass on a speaker that cannot play it. The speaker distorts or the phone’s protection kicks in, and the sound gets worse, not bigger.
Judging at very low volume. As the Fletcher–Munson experiments and the later ISO 226 contours show, our sensitivity to bass and extreme treble drops more than to the mids when the level is low. A curve that sounds balanced quietly may sound boomy when you turn it up.
Forgetting headroom. This one deserves its own section.

Avoiding clipping with a negative preamp

Digital audio has a hard ceiling, called 0 dBFS (decibels relative to full scale). Most commercial music is already mastered close to that ceiling. If you add +6 dB at 60 Hz, the bass peaks can now try to exceed the ceiling. Samples that would go above it are cut off flat – that is clipping, and it sounds like crackle or a harsh buzz on loud passages.

The fix is a preamp (or pre-gain) set below zero. A practical rule: lower the preamp by roughly the amount of your largest boost. If your highest band is at +6 dB, set the preamp to about −6 dB. The music will be a bit quieter, so raise the phone’s volume instead. The system volume is applied separately from the equalizer, so this keeps the equalizer itself from clipping. Some EQs do this automatically (“auto headroom”), and some add a limiter as a safety net – the subject of our article on bass boost without distortion.

What an EQ cannot do

An equalizer only reshapes what is already in the signal and what your speaker or headphones can reproduce. It cannot add detail that a low-quality file has lost, it cannot make a tiny speaker play deep bass, and it is not a substitute for checking your headphones fit properly. Used gently, though, it is the most effective tool you have for matching sound to your ears, your device and your room.

A note on volume

An equalizer makes it easy to raise the overall level without noticing. The World Health Organization’s Make Listening Safe guidance suggests keeping the volume down – for example, no higher than about 60% of your device’s maximum – and giving your ears regular breaks from loud sound. If you want to know more, read the WHO guidance directly.