How to read a frequency-response graph
A frequency-response graph shows how loud a headphone plays each pitch, from deep bass on the left to high treble on the right. The shape tells you the tonal character — where it is warm, neutral, or bright. A flat line is not the goal, and the graph does not tell you everything. Here is how to read one.
What the two axes are
The horizontal axis is frequency — pitch, in hertz (Hz), from 20 Hz (the lowest bass you can feel) to 20,000 Hz (the top of human hearing). It is spaced logarithmically, so each equal step is a doubling — 100, 200, 400, 800 — because that is how we hear pitch. The vertical axis is levelin decibels (dB): how loud the headphone plays that pitch relative to the rest. Higher on the graph means more of that region; lower means less. That is the whole language.
Reading it left to right
Four regions carry most of the character:
- Bass (20–250 Hz). Weight and warmth. More here reads as fuller and warmer; less reads as lean or clean.
- Mids (250 Hz–2 kHz). The body of voices and most instruments. Big dips or bumps here are the most audible of all, because this is where our hearing is most sensitive.
- Presence (2–5 kHz). Forwardness and “detail.” A rise pushes vocals toward you and can add bite; a dip pulls them back and softens the sound.
- Treble (5–20 kHz). Air, sparkle, and sibilance. A lift reads as bright and airy or, taken too far, sharp; a roll-off reads as smooth or dark.
Why a flat line isn’t the goal
This trips up almost everyone: a headphone that sounds neutral does not measure as a flat horizontal line. The measurement includes the response of the artificial ear and the rig it is measured on, and your own ear adds its own shape too. So instead of comparing a curve to a ruler, we compare it to a target curve— a shape that has been found to sound neutral or preferred (diffuse-field, Harman, or a house curve). A headphone that tracks the target sounds balanced; deviations from it are what you actually hear.
In practice a pleasant tuning is usually a gentle downward tilt — a little more bass than treble — not a flat line and not a wild zig-zag.
Peaks and dips: reading the shape
Once you stop expecting flat, the shape reads simply. A bump means more energy there (a bass bump = warmer; a presence bump = more forward; a treble bump = brighter). A dip means less (a mid dip = scooped or distant; a treble dip = smoother, darker). Narrow spikes above about 5 kHz are the least trustworthy part of any measurement — see the limits below — so read the broad trends first and treat the fine wiggles up top as directional, not exact.
The honest limits of any curve
A frequency-response graph is the most useful single measurement of a headphone, and it is still only part of the picture. Be honest about what it can and cannot resolve:
- The rig matters. Different measurement rigs give different curves for the same headphone, especially in the treble. Compare curves measured on the same rig, and note which rig you are looking at.
- Seating varies. How the headphone sits on the fixture (and on your head) shifts the response — a little in the mids, a lot above 10 kHz. Fine treble detail off a single curve is not settled fact.
- Open-backs read bass-light on some fixtures because the seal leaks. That can be the measurement, not the headphone.
This is why every graph in our Archive names its rig and its limits. A curve with its limits stated is worth trusting; a curve presented as gospel is not.
What a graph can’t tell you
Tonal balance is the graph’s home turf. Soundstage, imaging, detail, distortion, and comfort are not — those need other measurements or your own ears. So use the curve for what it is great at (is this bright or warm, forward or laid-back?) and do not ask it to settle questions it was never measuring.
And here is the honest catch: a graph is a line, and listening is personal. Two people reading the same curve want different things from it. That is why we built Attune — instead of guessing from the graph, you audition tunings blind and loudness-matched on your own music, and keep the shape you would actually pick by ear.
Hear a graph, don’t just read itThe honest bottom line
Read the axes, read the broad shape against a target, and trust the bass and mids more than the fine treble. The graph will reliably tell you a headphone’s tonal balance — warm or bright, forward or relaxed — and almost nothing about the rest. For the rest, you have to listen.
Common questions
What is a good frequency response for headphones?
There is no single “good” curve — it depends on your taste and the target you compare against. Many people prefer something close to a gentle downward tilt from bass to treble, but flatter-measuring is not automatically better. The graph tells you the character; whether you like it is the real question.
Why isn’t a headphone’s frequency response flat?
Two reasons. Real headphones have peaks and dips from their physical design, and the measurement includes the response of the ear and the rig — so a headphone that sounds neutral does not measure as a flat line. That is why curves are read against a target, not against a ruler.
What does a bump around 3 kHz mean?
That “presence” region controls how forward vocals and instruments sound. A bump there reads as more present or brighter; a dip reads as more distant or laid-back. Most tuning targets have some rise here by design.
Can you tell if a headphone is bright or bassy from the graph?
Yes — that is exactly what a frequency-response graph shows well. More energy on the left is more bass; a lift in the upper mids and treble reads as brighter. Tonal balance is the graph’s home turf.
What can’t a frequency-response graph tell you?
Plenty: soundstage, imaging, detail retrieval, distortion, comfort, and how a headphone holds together on busy passages. The graph is the single best predictor of tonal balance and a weak predictor of almost everything else.