Frequency response helps explain how headphones reproduce different parts of the audio spectrum. Technically, it measures output magnitude relative to input as frequency changes. If an input contains 100Hz, 1kHz, and 10kHz at equal amplitudes of -6 dB FS, headphones with a flat response would reproduce those frequencies at equal amplitudes.
The source's Raw Frequency Response test measures from 20Hz to 20kHz, approximately the limits of human hearing. Each headphone is re-seated and measured several times, with the results averaged into the final plot.
For a more accessible explanation of how these measurements translate into listening impressions, the source provides a Sound Profile article. Its R&D article explains the target curve used to assess that profile in greater detail.
Using Frequency Response to Choose Headphones
Although specialised equipment and a test rig make frequency response objectively measurable, interpreting it depends partly on preferences and intended use. Someone seeking more bass or less treble can examine those regions. Audio engineers may prefer a balanced or flat response for mixing and mastering, while gamers may favour elevated high bass to emphasise sound effects.
The source presents both raw response and sound profile measurements in its reviews. Raw graphs give experienced readers uncompensated data, with separate left and right driver responses that can help reveal how closely the drivers match.
The Sound Profile view instead applies the source's target curve, displaying that target as a straight line and the measured response as departures from it. This makes deviations easier to interpret.
Raw Graphs Versus a Sound Profile
The HiFiMan Sundara 2020 illustrates the difference:
 |  |  |
These plots show related frequency-response data in different forms. The left and right raw graphs remain uncompensated; the sound profile is adjusted against the target, shown as a flat dotted line.
Comparing Results and Recognising Limits
Raw response also makes comparisons with other reviewers easier, though different test rigs prevent reliable one-to-one comparisons. If you already enjoy headphones with a particular response, the source's Table Tool can help identify reviewed models with a similar shape.
For headphones reviewed under Test Bench 2.0 and later, the Graph Tool also allows comparisons with targets from other outlets, including SoundGuys.com. Understanding which response characteristics you enjoy can help guide future choices.
The Graph Tool highlights the highest treble region in yellow to flag measurement uncertainty. Differences in human ear morphology mean your experience in this range may not match the measured result.
Raw frequency response is an important part of headphone sound, but it does not explain everything. Learning to interpret the graph helps assess suitability for your needs; the source's sound quality glossary provides further context for the language used to describe frequency response.
Article Updates
- 06-03-2025: The source revised the article to reflect Headphones Test Bench 2.0 changes.
