Harman curve and dSONIQ Realphones
For many years, there have been discussions of the Harman curve among our users in social networks and forums, and we finally realized that we could not ignore this topic.

The Harman target curve is the idealized frequency response that headphones should have in order to give a tonally balanced sound. Headphones with the most flat frequency response subjectively sound too unimpressive, so the creators of the Harman Curve did research to figure out how to change the flat headphone frequency response target to get the best subjective experience.

Acoustic systems are the standard for listening and mixing music, so first, you need to understand what frequency response neutral-sounding speakers should have in real rooms.

Manufacturers configure studio monitors so that they have the most even frequency response in an anechoic chamber. This is the industry standard for tuning acoustic systems so that they reproduce recordings as reliably and naturally as possible.

If a column with a smooth anechoic frequency response is placed in a real room, then it falls into an environment with reflections. There is a rise in low frequencies due to reflection from the walls and absorption of high frequencies by air.
Approximately such a frequency response with a rise in low frequencies and a decline in high frequencies corresponds to tonally neutral reproduction in a real room.

The Harman curve was developed based on research that has been conducted for several years and included analysis of various headphones and subjective opinions of different listeners. The aim of this study was to determine the ideal target frequency response for headphones, which would provide balanced and accurate sound reproduction. The main approach for conducting the study was the use of low/high shelf filters in order, focusing on the listening experience of respondents, to adjust the frequency balance of headphones with aligned frequency response frequencies that have passed microphone measurements by ear.
On the graph, the black line is the preferred target frequency response for speakers, and the blue line is for headphones. In both cases, we see a rise in low frequencies and a decline in high frequencies.

But judging by the graph, it's not a linear frequency response, is it? Everything is right. This is a preferred curve, taking into account the lack of emulation of space and reflections in headphones. In fact, the researchers found such equalization settings to compensate for the absence of a room when listening with headphones.

If you use dSONIQ Realphones and apply binaural emulation of reflections and crossfeed signals (crossfeed) to the aligned frequency response of headphones, then you do not need to use the Harman curve.

Many manufacturers have released models customized for this curve. From full-size headphones, these are: AKG N700 NC, K361, and K371, and in-ear headphones: JBL Live 200, 500, and 650, Samsung Galaxy Buds, JBL Reflect Flow, Truthear x Crinacle ZERO.
The dSONIQ team is actively engaged in research and over the past 5 years we have measured and calibrated many models and different instances of headphones. Each calibration is a separate mini-study of how the human ear perceives a specific pair of headphones relative to calibrated monitors in more than 50 frequency bands.

We also measure anechoic frequency response. But what should be the curve so that the user's listening experience coincides with the sound of the speaker in a good room? Based on our technology, we get an accurate picture due to a large number of bands, which are compared with a built-up reference monitor system in the conditions of space emulation. Our auditory measurements have a much higher frequency detail than Harman's studies, in which only Low-Shelf and High-Shelf filters were tuned by ear.

Realphones is a combination of equalization and spatial simulation. We don't just measure anechoic frequency response, we get a calibrated listening environment. Due to the emulation of space, reflections of the room and the response of acoustic systems, we make it possible to get a really neutral and honest sound in headphones that you can trust.

Could say that our own analogue of the Harman curve is built into the reflections emulation. If the sound seems too dry when using Realphones, use the Brightness knob in Easy mode.

Realphones UI in Easy mode

If you turn off space emulation in advanced mode, raise the low frequencies and lower the high and medium ones, then in this way you can recreate the Harman curve using the plug-in.
Recreating the Harman curve by using Realphones
Realphones was originally conceived as a combination of correction and emulation. This gives the best listening experience and an effective result of the information. We are currently working on a new version of Realphones 2.0, in which we plan to create our own target frequency response curve, similar in tasks to the Harman curve. This will be a target neutral frequency response for use with Realphones correction without crossfeed, acoustic environment emulation and reflections.

Our research is not published in scientific journals, but it forms the basis for improvements in the dSONIQ Realphones technology. The best result for us is a constant increase in the number of users.

We would like to thank our readers who discuss such interesting topics and help our product become better.
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