Reading a Headphone Frequency Response Plot Without Overreacting

Read the shape, not the individual peaks, and a frequency response plot becomes useful rather than alarming. Almost every headphone deviates from a flat line somewhere, and a deviation is only a fault if it is broad enough and large enough to be heard against real programme material.

Understand what the measurement includes

Headphone measurements are taken on a coupler or an ear simulator, and the result contains both the headphone and the fixture. Above roughly 1 kHz the pinna, the ear canal and the seal dominate, which is why two rigs can disagree by several decibels in the same region.

Below 1 kHz the picture is more stable. The seal between pad and head still matters, but a good coupler reproduces the low end closely enough to compare units against each other on the same rig.

The practical rule: trust comparisons made on one rig, and treat absolute values from different rigs as approximate.

Compare against a target, not against flat

A flat line measured at the eardrum is not what a listener perceives as neutral, because the outer ear reinforces certain bands. Most published targets therefore rise slightly toward the low end and show a broad elevation around 2 to 4 kHz.

Read a plot by asking how far the curve sits from the target in three broad bands: under 200 Hz, from 200 Hz to 1 kHz, and above 1 kHz. A 3 dB difference spread over an octave is audible. A 6 dB spike a tenth of an octave wide often is not.

Look for the three informative regions

The bass shelf tells you about seal and tuning intent. A lift under 100 Hz adds weight; a roll-off under 60 Hz suggests the seal is broken or the design is deliberately lean.

The upper midrange around 2 to 4 kHz decides perceived clarity and vocal placement. Too much there sounds forward and fatiguing; too little sounds distant and soft.

The presence region from 5 to 10 kHz decides how much air and detail you perceive. A narrow peak causes sibilance and fatigue. A broad dip makes cymbals sound dull.

Everything above 10 kHz is unreliable on most rigs. Do not choose a headphone on that part of the chart alone.

Watch the artefacts around the plot

Channel matching matters more than most people expect. A 2 dB difference between left and right in the midrange shifts the stereo image and is often reported as a channel imbalance in the recording rather than in the headphone.

Distortion curves belong next to the response curve, not in a separate review. A driver that measures cleanly at 90 dB can behave quite differently at 105 dB, and that is the level where most complaints about hardness originate.

Waterfall plots show decay over time and are useful for spotting stored energy in the cup, but they are easy to over-read. A visible ridge is only a problem when it lines up with a peak in the response.

Turning a plot into a decision

Pick two or three points on the curve that match what you hear in your own reference tracks, and use those points to compare candidates. Ignore everything else until the shortlist is down to three pairs.

Then listen. A plot predicts the direction of a difference, not the size of your reaction to it.

Where the plot stops being useful

Above roughly 8 kHz the measurement depends heavily on the individual ear and on the exact position of the headphone. Two runs on the same rig with a two-millimetre repositioning can differ by several decibels.

Below 40 Hz the seal and the ambient pressure dominate. A plot measured on a loose fit will show a roll-off that has nothing to do with the driver.

So the reliable region is roughly 40 Hz to 8 kHz, and within that region the shape rather than the exact value is what you should read.

Keeping your own measurements

Measure the headphones you own before shopping. A baseline of your own reference pair makes every comparison concrete rather than abstract.

Record the measurement conditions alongside the plot: the rig, the fit, the level and the software version. Without those, a measurement cannot be reproduced even by the person who made it.

Then compare candidates against your own baseline rather than against an ideal curve. The relative difference tells you what to expect in your own room and on your own source.