How to read a frequency response graph.

Anatomy of a frequency response graph

A headphone frequency response graph plots two things against each other: which frequencies the headphone is reproducing (horizontal axis) and how loudly it's reproducing each one (vertical axis). The line drawn across the graph is the headphone's "fingerprint" — every headphone has a unique shape, and that shape tells you what to expect when you put them on.

How the measurement is made: engineers play a precisely-defined test signal through the headphone — typically a "frequency sweep" that smoothly rises from 20Hz to 20,000Hz at a constant electrical level. A measurement microphone inside an artificial ear (technically called a "head and torso simulator" or HATS) captures what reaches the eardrum at each frequency. The result is plotted as a continuous line showing how the headphone deviates from the input signal across the audible spectrum.

A perfectly transparent headphone would reproduce every frequency at exactly the same level — a flat horizontal line. No real headphone does this, and as we'll see, you wouldn't actually want one that did. But understanding what shape the line takes, and how to read those shapes, gives you a real predictive tool when you're shopping.

Reading the axes (don't skip this)

Frequency response graphs use specific conventions that confuse first-time readers. Understanding the axes is the prerequisite for everything else.

The horizontal (X) axis: frequency in Hertz. The numbers usually run from 20 (bottom of human hearing) on the left to 20,000 (top of human hearing) on the right. Critically, this axis is logarithmic, not linear. The distance from 20Hz to 200Hz on the graph is the same as the distance from 2,000Hz to 20,000Hz — even though the second range covers 18,000Hz and the first covers only 180Hz.

This matters because the logarithmic scale matches how human hearing actually works. Your ear perceives a doubling of frequency as the same musical interval (an octave) regardless of where on the spectrum it happens. The jump from 100Hz to 200Hz sounds like the same "step up" as the jump from 1,000Hz to 2,000Hz. The logarithmic graph reflects that perception.

Practical implication: bass frequencies (20-200Hz) take up the left third of the graph; midrange frequencies (200-2,000Hz) take up the middle third; treble frequencies (2,000-20,000Hz) take up the right third. Three roughly equal-width regions on the graph, despite covering wildly different frequency spans.

The vertical (Y) axis: relative loudness in decibels (dB). The numbers typically span 30dB total — often from -20dB at the bottom to +10dB at the top, with 0dB representing the headphone's reference average level. Higher on the graph means the headphone is louder at that frequency; lower means quieter.

The decibel scale is also logarithmic, but in a way that matters for perception: every 3dB difference roughly doubles the perceived loudness. A frequency that's 6dB higher than another sounds 4x as loud; 10dB higher sounds 10x as loud. Small-looking bumps on the graph (3-6dB) are audible. Large bumps (10dB+) are dramatic.

Practical implication: when comparing two headphones, focus on differences of 3dB or more. Differences under 2dB are usually inaudible. Differences of 6dB+ in the same region (especially bass and treble) define what makes one headphone sound clearly different from another.

What "flat" actually means (and why you don't want it)

New audiophiles often assume "flat frequency response" — a perfectly horizontal line across the graph — is the ideal headphone tuning. It isn't. A truly flat headphone sounds wrong because your ears don't perceive sound flatly.

Here's why. Imagine you're listening to music through high-quality loudspeakers in a treated room. The sound travels through the air, bounces off room surfaces, enters your ear canal, and reaches your eardrum. Along that path, the sound is shaped by your head, your outer ear (pinna), and your ear canal itself. Different frequencies are affected differently by this acoustic journey — your outer ear naturally emphasizes frequencies around 2-4kHz (where speech intelligibility lives), and your ear canal resonates around 3-7kHz.

A flat speaker in a treated room actually produces a non-flat signal at your eardrum, because your anatomy does the shaping. Your brain expects this shaping and uses it to construct natural-sounding audio.

A headphone driver sits a few millimeters from your ear canal, bypassing most of that natural acoustic shaping. To sound natural, a headphone needs to artificially recreate what your outer ear would have done if you were listening to speakers. That means a headphone with "flat" output at the eardrum needs elevated output around 2-4kHz to mimic the natural ear gain.

The implication: a measurement graph showing a perfectly flat line is actually showing a headphone that will sound wrong — typically described as "thin," "lacking presence," or "missing midrange." A well-tuned headphone shows a specific non-flat shape called a "target curve" that compensates for normal ear anatomy.

Target curves and the Harman research

Several research efforts have tried to scientifically define what shape headphones should produce. The most influential is the Harman International research, led by Sean Olive, which has shaped modern headphone tuning more than any other single source.

Olive and his team conducted blind listening tests with hundreds of trained and untrained listeners, asking them to rate equalizer-modified headphone responses for preference. By statistically aggregating these preferences, they derived target curves for both over-ear and in-ear headphones — frequency response shapes that consistently scored highest across diverse listener populations.

The resulting "Harman target curve" for over-ear headphones has these characteristic features:

• Slightly elevated bass (about +6dB at 20-100Hz, gently rising into the lowest frequencies) — listeners prefer modest bass emphasis
• Reference-level midrange (roughly 200-800Hz at 0dB) — clear vocal reproduction
• Elevated presence region (+8 to +10dB peak around 2-3kHz) — compensating for natural ear gain
• Slightly rolled-off treble (gradually descending above 4kHz) — avoiding harshness while preserving detail
• Gentle high-frequency presence (small emphasis around 8-10kHz for "air")

A headphone that closely matches this shape will sound subjectively "good" to most listeners, regardless of training or experience. Headphones that deviate significantly from it will be polarizing — some listeners love them, others find them objectionable.

The Harman target isn't universally accepted. Some audiophiles prefer the older "diffuse field" target, which has more elevated treble. Some prefer the "JBL house curve" with stronger bass. Specific use cases (mixing, mastering, studio reference) often favor flatter responses that don't apply Harman bass emphasis. But for general consumer listening, Harman remains the closest thing to a scientifically-validated target.

Practical takeaway: when reading frequency response graphs, having the Harman target overlaid (which RTINGS and many other measurement sites do) lets you quickly see how a headphone deviates from "preferred neutral." Differences become meaningful when they exceed 3-5dB in any region.

The frequency regions and what they mean

To read graphs intuitively, you need to know what kinds of musical content live in each region of the spectrum, and what bumps or dips in each region actually sound like.

Sub-bass and bass (20-250Hz)

The bottom octaves of music — kick drum fundamentals, bass guitar low strings, synth bass lines, the rumble of cinema sound design.

Sub-bass (20-60Hz): The deepest content, more felt than heard. Most "bass headphones" fail here — they boost mid-bass (which is easy) without extending into sub-bass (which is hard and requires capable drivers). Read graphs in this range carefully: a headphone that maintains output within 3dB of reference down to 30Hz has real bass extension. One that rolls off (drops below -6dB) above 50Hz is fakingbass with mid-bass boost. We cover this distinction in detail in our bass & EDM guide.

Mid-bass (60-150Hz): The "thump" region. Kick drum body, electric bass fundamentals, the punch of 808 samples. This is where most "bass headphones" do their work — boosting 80-150Hz creates impressive perceived bass even when sub-bass is weak. A modest 3-6dB bump here matches the Harman target's bass emphasis. Bumps above 6dB start sounding bloated; above 10dB becomes thumpy and unrealistic.

Upper bass (150-250Hz): Bass guitar harmonics, lower piano notes, the lower fundamentals of acoustic instruments. Excess energy here makes a headphone sound "muddy" or "thick" — male vocals lose clarity, bass becomes indistinct, the whole sound feels congested. Cheap bass-marketed headphones often have problems in this region. A flat or slightly dipped response here is usually preferred.

Midrange (250-4,000Hz)

Where most musical information lives — vocals, piano, guitar, brass, and the fundamental tones of most instruments. The most perceptually sensitive region of human hearing. Small changes here have outsized effects on how natural a headphone sounds.

Low mids (250-500Hz): Lower vocal range, body of acoustic guitars, low brass. Excess energy here creates "honk" or "boxiness" — male vocals sound nasal, instruments sound recessed in their own bodies. Most well-tuned headphones are flat through this region.

Middle mids (500-2,000Hz): Where most vocals live, and where most instrumental fundamentals sit. The Harman target gradually rises through this region (starting from 0dB at 500Hz, rising to +5-7dB at 2kHz). Headphones with major dips here sound "scooped" — vocals get pushed back in the mix, the music sounds distant. Headphones with peaks here sound forward and aggressive.

Presence region (2,000-4,000Hz): Speech intelligibility, vocal clarity, the attack of plucked strings. This is where the ear's natural gain peaks, and where the Harman target shows its biggest elevation (+8-10dB). Headphones that fail to elevate here sound "muffled" or "dull." Headphones that over-elevate (more than +12dB) sound harsh or aggressive.

Treble and air (4,000-20,000Hz)

The top octaves — cymbal shimmer, vocal sibilance, the "air" around acoustic recordings, the detail that separates a great recording from a merely good one.

Lower treble (4,000-8,000Hz): Vocal sibilance ("S" and "T" sounds), cymbal stick attacks, the edge of distorted electric guitars. Headphones with peaks here can sound "harsh" or cause ear fatigue during long sessions. Headphones with dips here sound "smooth" or "warm." The Harman target has a gentle descent through this region after the presence peak.

Upper treble (8,000-12,000Hz): Cymbal shimmer, the high harmonics of strings and brass, the sense of detail and spaciousness. Headphones that emphasize this region sound "detailed" or "airy"; ones that roll off here sound "intimate" or "warm."

Air (12,000-20,000Hz): The very top of human hearing — most adults lose sensitivity here with age. A gentle peak in this region (a few dB) gives headphones a sense of "air" or "openness." A dip here removes that sense without much else changing.

Reading treble accurately is harder than reading bass and midrange. Measurement variability in the treble region is significant — different microphones, different mounting positions, and different test fixtures can produce noticeably different treble readings of the same headphone. Trust multiple sources rather than relying on a single graph for treble assessment.

Common headphone tuning shapes

Once you've internalized the regions, several common tuning signatures become recognizable at a glance. These shapes correspond to the marketing categories headphones are often sold under.

"Neutral" or "reference" tuning — closely follows the Harman target. Examples: Sennheiser HD 650, HD 560S, Audeze MM-100. Graph shows modest bass elevation (4-6dB), flat midrange, +7-10dB presence peak around 2-3kHz, gradual roll-off above 8kHz. Sounds balanced and natural; preferred by working audio professionals and listeners who value accuracy.

"V-shaped" or "consumer" tuning — boosted bass and boosted treble with a recessed midrange. Examples: Beats Studio Pro, Sony WH-XB910N, many Bose consumer products. Graph shows +8-12dB at bass peaks, dipped midrange (vocals slightly pulled back), then elevated treble. Sounds "exciting" or "fun" in short demos but can be fatiguing over long sessions and makes vocals feel distant.

"Warm" tuning — elevated bass with rolled-off treble. Examples: Meze 99 Classics, ZMF Aeolus, vintage Audeze planars. Graph shows elevated bass, normal midrange, and gentle treble roll-off above 5kHz. Sounds smooth and easy on the ears; flattering for poorly-recorded material; can lack detail and air.

"Bright" or "analytical" tuning — flat or slightly recessed bass with elevated treble. Examples: Sennheiser HD 800 S, Beyerdynamic DT 990 Pro (vintage), AKG K701. Graph shows lean bass, accurate midrange, and noticeably elevated 5-10kHz region. Sounds detailed and articulate; can sound thin or fatiguing depending on listener sensitivity and source material.

"Studio" tuning — close to neutral but with stronger high-frequency presence for catching mix problems. Examples: Sony MDR-7506, Shure SRH440A. Graph shows accurate bass and midrange with an elevated upper treble (around 5-8kHz) that helps engineers hear sibilance and detail. Useful for tracking and editing; less ideal for casual listening.

"Bass head" tuning — extreme bass boost with everything else recessed. Examples: many "extra bass" consumer headphones, some pro DJ headphones. Graph shows +10-15dB at bass peaks, with the elevated bass extending into the lower midrange in ways that mask vocals. Useful for specific genres (EDM at high volume) but unflattering for most music.

Measurement sources you can actually trust

Where you get your frequency response graphs matters as much as how you read them. Manufacturer-published graphs are essentially never trustworthy — they're either generated under ideal conditions to look better than reality, or they're stylized marketing illustrations not based on real measurements at all.

Trustworthy sources, in rough order of usefulness:

RTINGS.com — the most comprehensive headphone measurement database online. Uses standardized test equipment (Brüel & Kjær HATS), publishes detailed methodology, and includes hundreds of mainstream and audiophile headphones. Their graphs include the Harman target overlay so you can see deviations at a glance. Free access, no subscription required. The first place to check for almost any headphone in mass production.

Crinacle.com — Crinacle (Crinion) maintains an extensive measurement database focused on IEMs and audiophile headphones. Uses a IEC 60318-4 711 coupler (the standard for audiophile measurements) and publishes graphs in a clean, comparable format. Best source for IEM measurements specifically. Crinacle also maintains a rankings list that's controversial in audiophile circles but worth understanding.

Audio Science Review (ASR) — forum-based community focused on objective measurement. The "headphone measurement index" thread aggregates hundreds of measurements from multiple contributors. Quality is variable but the methodology discussions are rigorous, and outlier measurements get scrutinized. Good for audiophile and reference-grade headphones; less complete for mainstream consumer products.

Reference Audio Analyzer — Russian site maintained by Roman Khalupkin, with one of the largest databases of headphone measurements online. Methodology is well-documented and consistent. The site interface can be challenging for English speakers but the data is excellent.

oratory1990 (Reddit) — engineer who publishes high-quality measurements with calibrated equipment, available through r/oratory1990 on Reddit and his measurement page. Strong for premium audiophile headphones, less comprehensive than RTINGS for mainstream products.

Less reliable but sometimes useful: SoundGuys (publishes their own measurements but methodology has evolved over time), Inner Fidelity (now defunct but archived measurements still circulate), individual YouTube reviewers (variable quality and methodology).

To avoid: any frequency response graph published by the manufacturer themselves, any review site that doesn't publish measurement methodology, and any source that shows perfectly smooth, idealized response curves without normal measurement variation visible.

What frequency response graphs don't tell you

Frequency response is the single most important measurement for predicting how a headphone will sound — but it's not the complete picture. Several things matter for the listening experience that don't show up in a frequency response graph.

Distortion. A frequency response graph shows how loudly the headphone reproduces each input frequency, but not how cleanly. Two headphones with identical frequency response can have very different distortion characteristics. Premium dynamic and planar headphones typically have low distortion; cheap headphones often have audible distortion at high volumes. Look for separate "Total Harmonic Distortion" (THD) measurements alongside frequency response.

Transient response. How quickly the driver starts and stops moving. Headphones with poor transient response sound "slow" or "smeared," even if their frequency response looks identical to faster headphones. Planar magnetic and balanced armature drivers generally have better transient response than dynamic drivers. Not visible in standard frequency response graphs; sometimes shown separately as "impulse response" measurements.

Soundstage and imaging. The perception of where instruments are located in three-dimensional space. Open-back headphones generally have wider soundstage than closed-back; large drivers generally have better imaging precision than small ones. Not measurable in any single graph — it's a result of the headphone's whole design including ear cup shape, driver positioning, and acoustic damping.

Sensitivity to source/amp. How the headphone responds to different amplification. Some headphones (especially high-impedance audiophile designs) sound dramatically different on different amplifiers. The same headphone measured on the same coupler will produce essentially identical frequency response regardless of amp — but the listening experience can vary substantially. See our impedance and sensitivity guide for context.

Comfort and fit. Obviously not visible on any graph. Yet a headphone that's uncomfortable to wear for 30 minutes won't matter how well it measures. Always check comfort reviews alongside frequency response data.

Build quality and longevity. Frequency response can't tell you whether the cups will crack in 18 months or whether the manufacturer stocks replacement pads. Check long-term ownership reviews and parts availability before any premium purchase.

Tuning consistency. Individual unit-to-unit variation can be significant, especially for cheaper headphones. The graph you see represents one specific unit measured under specific conditions. Your headphone might measure slightly differently due to manufacturing variation, age, and pad condition. RTINGS and similar sources sometimes publish "unit variance" data showing how much different units of the same model differ.

FAQ

Why do different measurement sources show different graphs for the same headphone?

Several factors. Different measurement rigs (Brüel & Kjær HATS, IEC 711 coupler, GRAS 43AG) measure slightly differently, especially in the treble region. Pad condition affects the seal and changes the response. Mounting position on the test head affects the bass response. Individual unit variation contributes. The result is that measurements of the same headphone from different sources can differ by 1-3dB in some regions. The general shape should agree across reputable sources; only worry when major shape differences appear, which usually indicates methodology problems.

Can I trust the frequency response graph to predict how I'll hear it?

For 80% of the listening experience, yes. The graph predicts tonal balance accurately — whether bass will be heavy, midrange will be forward, treble will be sparkly. What the graph doesn't predict: how distortion will affect loud listening, how soundstage will feel, whether the headphone will be comfortable, and your personal preferences for tonal character. Use the graph as the foundation for prediction, then layer in subjective reviews and (ideally) your own demo listening to confirm.

Why don't manufacturers publish reliable frequency response graphs?

Three reasons. First, real measurements often look worse than marketing illustrations — non-ideal frequency response is the norm, and most manufacturers don't want to publish data that lets buyers compare them objectively. Second, measurement standards aren't universal — what looks "flat" on one coupler looks bumpy on another, so there's no agreed format. Third, the audiophile review community has effectively taken over independent measurement, so manufacturers don't need to publish their own data — RTINGS, Crinacle, and similar will measure it anyway. The result is that consumer trust in independent measurement is high and manufacturer-published graphs are rightly treated as marketing.

Should I EQ my headphones to match the Harman target?

Sometimes useful, often not. EQ can shift a headphone's tuning closer to Harman-target preferences, and many enthusiasts find this improves their listening experience. But EQ can't fix fundamental driver limitations — a headphone that physically can't produce 30Hz will still roll off below that frequency no matter how much you boost it. The "AutoEQ" project (github.com/jaakkopasanen/AutoEQ) provides parametric EQ presets that move many popular headphones toward Harman target. Try it if you're curious; expect modest improvements rather than transformation.

Why is RTINGS' graph different from Crinacle's for the same headphone?

Different measurement equipment and presentation styles. RTINGS uses a Brüel & Kjær Type 4128-C HATS with their own derived target curve. Crinacle uses an IEC 60318-4 (711) coupler with a different target reference (his own "preference" curve). The actual headphone response is the same; the way it's displayed and what it's being compared to differs. For headphones, RTINGS' presentation is usually easier to read; for IEMs specifically, Crinacle's is more standardized with the IEM measurement community.

Are wireless headphone graphs harder to interpret?

Slightly, because wireless headphones often have built-in EQ or DSP processing that changes the response depending on Bluetooth codec, app settings, or noise cancellation mode. The graph you see represents specific settings; your real-world listening might use different ones. RTINGS typically measures in multiple modes (ANC on/off, app EQ disabled) to show the range. For wireless headphones, pay attention to the measurement conditions and check the same conditions you plan to use.

Is there a "perfect" headphone tuning?

The Harman target is the closest thing science has produced to "preferred neutral" across diverse listener populations. But individual preferences vary — some listeners prefer more bass, some prefer more treble, some prefer less Harman ear-gain emphasis. The "perfect" tuning is the one that matches your specific preferences for your specific music, on your specific equipment, in your specific listening environment. The Harman target is the best starting point; deviations from it become valid based on your own ears.

Bottom line

A frequency response graph is the closest thing to objective truth in headphone reviewing. Once you can read one — understand what the axes show, recognize common tuning shapes, know which sources to trust — you have a real predictive tool when shopping for headphones.

The skill levels up gradually. Beginners can learn to identify "bass-heavy" vs "neutral" vs "bright" tunings at a glance. Intermediate readers can identify specific frequency-region characteristics (recessed midrange, presence peak, treble roll-off) and predict how they'll sound. Advanced readers can spot the subtle deviations from preferred targets that distinguish, say, a Sennheiser HD 600 from an HD 650.

For practical shopping: when considering any headphone above $100, find at least one independent measurement (RTINGS first, then Crinacle, ASR, or oratory1990) and compare it to the Harman target. Look at where it deviates and ask yourself whether those deviations align with what you want. A headphone with +6dB bass and gentle treble roll-off will sound warm and impactful. One with flat bass and elevated treble will sound analytical and detailed. Neither is universally "better" — but knowing which shape you're buying prevents the disappointment of headphones that don't match what you actually want.

Frequency response isn't the only thing that matters — comfort, build quality, driver technology, distortion, and your specific musical preferences all contribute. But it's the single most informative measurement, and it's freely available for nearly any headphone you'd consider buying. Spending 10 minutes reading the graph before a major purchase is one of the highest-leverage activities in headphone shopping. You'll know roughly what you're buying before it arrives.

The hobby has its share of subjective claims and audiophile mythology. Frequency response graphs are where the science is actually rigorous, where the data is actually reliable, and where you can actually train your intuition against measurable reality. Learn to read them and the rest of the audio world starts to make more sense.