Submission declined on 31 December 2025 by WeirdNAnnoyed (talk). This draft's references do not show that the subject meets Wikipedia's criteria for inclusion. The draft requires multiple published secondary sources that: provide significant coverage: discuss the subject in detail, not just brief mentions or routine announcements; are reliable: from reputable outlets with editorial oversight; are independent: not connected to the subject, such as interviews, press releases, the subject's own website, or sponsored content. Please add references that meet all three of these criteria. If none exist, the subject is not yet suitable for Wikipedia. This draft appears to contain text generated by a large language model (such as ChatGPT). You cannot use LLMs to generate article content. LLM-generated pages with certain obvious signs of being machine generated may be deleted without notice. These tools are prone to specific issues that violate our policies: hallucinations: they often invent false information and cite non-existent references. unencyclopedic tone: they tend to be vague, promotional, or essay-like, rather than neutral and factual. copyright issues: they may closely paraphrase existing text, leading to copyright violations. Instead, only summarize in your own words a range of independent, reliable, published sources that discuss the subject. See the advice page on large language models for more information. If you would like to continue working on the submission, click on the "Edit" tab at the top of the window. If you have not resolved the issues listed above, your draft will be declined again and potentially deleted. If you need extra help, please ask us a question at the AfC Help Desk or get live help from experienced editors. Please do not remove reviewer comments or this notice until the submission is accepted. Where to get help If you need help editing or submitting your draft, please ask us a question at the AfC Help Desk or get live help from experienced editors. These venues are only for help with editing and the submission process, not to get reviews. If you need feedback on your draft, or if the review is taking a lot of time, you can try asking for help on the talk page of a relevant WikiProject. Some WikiProjects are more active than others so a speedy reply is not guaranteed. How to improve a draft Wikipedia:Contributing to Wikipedia – a basic overview on how to edit Wikipedia. Help:Wikitext – how to use the markup Help:Referencing for beginners – how to include references Wikipedia:Article development – how to develop your article Wikipedia:Writing better articles – how to improve your article Wikipedia:Verifiability – make sure your article includes reliable third-party sources You can also browse Wikipedia:Featured articles and Wikipedia:Good articles to find examples of Wikipedia's best writing on topics similar to your proposed article. Improving your odds of a speedy review To improve your odds of a faster review, tag your draft with relevant WikiProject tags using the button below. This will let reviewers know a new draft has been submitted in their area of interest. For instance, if you wrote about a female astronomer, you would want to add the Biography, Astronomy, and Women scientists tags. Add tags to your draft Editor resources Easy tools: Citation bot (help) | Advanced: Fix bare URLs Declined by WeirdNAnnoyed 5 months ago. Last edited by WeirdNAnnoyed 5 months ago. Reviewer: Inform author. Resubmit Please note that if the issues are not fixed, the draft will be declined again.

Submission declined on 28 December 2025 by TheInevitables (talk). This draft reads like an essay or opinion piece. Wikipedia is not a place for original research or personal opinions. The draft should: summarize secondary sources: do not offer your own analysis or arguments; be written from a neutral point of view: represent the subject without bias, avoiding praise, criticism, or persuasive or promotional language; not contain original research: do not include new theories, unpublished ideas, or personal experiences. Instead, only summarize in your own words a range of independent, reliable, published sources that discuss the subject. Declined by TheInevitables 5 months ago.

• Comment: The article is based entirely on primary sources (except maybe Ref. 7/15, but I don't know about the reliability of that website). The Acoustics Today article comes up as a 404. I strongly suspect these are AI-suggested references, but can't be certain. Regardless, we need secondary sources for an article. Primary sources are fine to verify statements of fact, but not for notability. Also, the article is far too technical for a general audience. The "measurement methodology" and "target response curves" could be omitted entirely with no loss of quality. WeirdNAnnoyed (talk) 22:47, 31 December 2025 (UTC)

Headphone frequency response is a measure of the sound pressure level (SPL) produced by headphones across the audible frequency range relative to a constant input signal. It is a key objective specification used to characterize the tonal balance and timbre of electroacoustic transducers. Unlike loudspeakers, which are typically designed to achieve a flat frequency response in an anechoic environment, headphone response targets are designed to compensate for the acoustic effects of the human head, ear canal, and torso that are bypassed during headphone listening.

Frequency response represents the transfer function of the headphone system. It is graphically displayed as a curve where the horizontal axis represents frequency (typically 20 Hz to 20 kHz) and the vertical axis represents sound pressure level in decibels (dB). A specific tolerance (e.g., ±3 dB) is required to meaningfully characterize the fidelity of the reproduction, as the nominal frequency range alone does not indicate linearity.^[1] Graphically it is represented as a frequency response curve, where:

• the horizontal axis (X) shows frequency in hertz (Hz) on a logarithmic scale, typically from 20 Hz to 20 kHz, which corresponds to the nominal range of human hearing
• the vertical axis (Y) shows sound pressure level (SPL) in decibels (dB).^[2]

Measuring headphone frequency response is technically more demanding than measuring loudspeakers, because the measurement microphone cannot simply be placed in front of the driver. Specialized equipment defined by international standards is used.^[3][4]

Headphone frequency response is measured using specialized equipment defined by international standards, as the microphone cannot be placed in the far field as with loudspeakers. Measurements are typically performed using head-and-torso simulators (HATS) or ear simulators that replicate the acoustic impedance and resonance of the human ear.^[3][5]

• IEC 60318‑4 (formerly "IEC 711") defines occluded-ear simulators for inserting headphones (in-ear monitors). These couplers simulate the average human ear canal, including its primary resonance at approximately 13.5 kHz.^[6]
• HATS systems such as the Brüel & Kjær 5128 or GRAS 45CA, utilize anatomical pinnae and ear canals. These systems are required for measuring circumaural (over-ear) and supra-aural (on-ear) headphones to capture the acoustic effects of the outer ear on high-frequency response.^[3][5]

Measurement data is typically presented in two forms:^[4][7]

• Raw response: The direct sound pressure level measured by the microphone. Due to ear canal resonance, raw measurements of neutral headphones typically exhibit a significant peak around 3 kHz.
• Compensated response: The raw measurement normalized against a specific target curve (e.g., Diffuse Field or Harman target). A compensated curve approaching a flat line indicates adherence to the target response.^[4][7]

Headphone frequency response targets represent theoretical curves intended to produce neutral or listener-preferred tonal balance. Unlike loudspeakers designed for flat response in anechoic conditions, headphone targets compensate for the absence of head-related acoustic cues present during room listening.^[8]

The free field target assumes headphones should simulate the response of an ideal loudspeaker measured in an anechoic chamber at the listener's ear. Headphones tuned to this target typically reproduce the ear's natural resonance but lack the bass reinforcement provided by room acoustics, often resulting in a perceived lack of bass.^[9][10]

Developed in the 1980s, the diffuse-field target models the response of a loudspeaker in a reverberant room where sound arrives from all directions with equal probability. While headphones such as the Etymotic ER4 or Sennheiser HD 600 approximate this curve, psychoacoustic tests suggest the DF target is frequently perceived as too bright and bass-deficient compared to calibrated loudspeaker setups.^[9][11]

Separate target curves exist for different headphone form factors. For over-ear headphones, the Harman target specifies a bass shelf (+4 to +6 dB below 200 Hz), a "pinna gain" peak of approximately +10 dB at 3 kHz to replicate outer ear resonance, and a gradual high-frequency roll-off. In contrast, the target for in-ear monitors (IEMs) requires a modified response curve with adjusted bass and treble levels, as the insertion of the device into the ear canal bypasses the acoustic effects of the pinna (outer ear) and alters the natural resonance of the ear canal.^{[11][12][13][14]}

Different parts of the frequency spectrum influence different aspects of the listening experience:^[15][16]

• Sub‑bass (20–60 Hz): provides physical impact and perceived weight. Excessive gain causes boominess; insufficient levels result in thin timbre.^[15]
• Bass (60–250 Hz): carries fundamental tones and rhythm. Overemphasis produces muddiness and masking; underemphasis yields analytical character.^[15][16]
• Low‑mid and midrange (250 Hz–2 kHz): contains primary vocal and instrumental body. Peaks create honkiness; dips produce veiled timbre.^[16]
• Upper midrange and presence region (2–6 kHz): affects clarity and source distance perception. Excessive gain causes fatigue; recess produces muffled quality.^[17]
• Lower treble (6–10 kHz): determines brightness and transient attack. Peaks induce sibilance; recess reduces detail perception.^[15][17]
• Upper treble (10–20 kHz): contributes spatial airiness. Measurements show high sensitivity to positioning; listener sensitivity also diminishes in this range.^[18]

While frequency response is a primary objective metric, high-frequency measurements (typically above 10 kHz) exhibit significant variance due to positioning sensitivity on test fixtures. Furthermore, individual ear canal geometry and acoustic impedance differ from standard couplers, meaning headphones with a flat response on a simulator may not be perceived as neutral by all listeners, particularly with in-ear monitors..^{[19][20][21][22]}

In consumer audio, particularly with True Wireless Stereo (TWS) devices, digital signal processing (DSP) is frequently employed to correct frequency response deviations. This allows manufacturers to compensate for driver limitations and approximate target response curves through active equalization.^[23][24]

Research analyzing large datasets of commercial headphones has found no significant correlation between retail price and adherence to preferred frequency response targets. This suggests that higher cost does not necessarily predict superior tonal balance or objective sound quality.^[25]