Harman Curve; A Frequency Response Standard for Headphones: Beginner’s Explanation

Over the years, Harman had a mission: to find the best frequency response measurement for speakers and headphones. And in 2012, scientists working on headphone sound quality discovered the Harman Curve. If you’re not the average type of headphone user and you’re looking for pure quality then you must learn about the Harman Curve along with the history of the Harman Curve before you make a purchase.


About Harman Curve

The Harman Curve is defined as the best sound signature that users prefer to listen to when using headphones. This is the closest representation of how top-quality speakers should sound like inside a room.

The Harman Curve determines the target frequency response curve of headphones and pinpoints what levels must be enhanced and which should be reduced. Another name for the Harman Curve is the Harman target and is known as the ideal frequency response to enjoy music from your headphones.

Harman Curve has many characteristics: it has a slightly increased bass sound and an elevated treble.

Related: Headphone and Speaker Crossover Frequency

Why scientists created the Harman Curve?

You may have seen, heard about, and used Harman audio devices. The brand is synonymous with fine audio, the best replication of sound. Harman, in its quest for the best sound measurement, started research on how to get the best output in headphones.

Harman concluded that tuning for speakers does not apply to headphones. Tuning a headphone is difficult due to the difference in the human anatomy. Because of our unique physiologies, scientists say that there may be 2 decibels differences in the way we perceive a variety of frequencies.

Headphones are different from speakers as the sound it makes only interacts with the ear canal and the pinna. Earbuds only interact with the ear canal as the sound moves through this structure.

There are four Harman Curves, each of these curves has slight variations depending on what people want to hear. In the most recent iteration of the Harman Curve in 2019, there was a higher bass boost and a seamless treble frequency.

Harman Curve survey results

Meanwhile, Harman also studied the characteristics of different users. About 64% of users, from everyday listeners to professional users were pleased with the Harman Curve. Most of the Harman Curve enthusiasts belong to the ages 50 years and below.

Around 15% of users wanted more bass and most of these listeners were younger male users. The remaining percentage wanted less bass and most of these listeners were females and older individuals.

Headphones Using Harman Curve

Not many headphones have adapted to the Harman Curve but if you take a closer look at some high-end models, you’ll see that these have almost the same frequency responses.

Harman also uses other variations on its products. This is because every user is different as they hear differently. You can't create a universal type of headphones for all types of users.

The following are headphone models that use the Harman Curve

AKG N5005 In-Ear Headphones

AKG by Harman has the N5005 In-Ear Headphone, a 5- driver hybrid headphone that will give you balanced sounds layer after layer. You’ll enjoy balanced pure sounds no matter what genre you want to listen to.

Enjoy customizable filters that let you adjust midrange to high notes according to your tastes. The N5005 comes with a 10Hz to 40Hz dynamic frequency response range, 18 ohms impedance, and a 9.2mm driver with a quad-balance armature.

This is a wireless Bluetooth headphone that weighs barely anything so you can easily wear it anywhere, in any activity.

AKG K371 Closed-Back Headphones 

The K371 from AKG is a professional listening tool used for highly specialized audio recording and listening. It is a wired studio headphone you can use to make podcasts, for critical listening, and professional music production.

This headset reproduces sounds with the highest fidelity using its 50mm titanium-coated dynamic drivers and OFC voice coil. It is perfect for sound production as it can isolate ambient noises to enhance bass response and avoid any low-frequency sounds from affecting your mixes.

The K371 comes with the AKG Reference Response Curve headphone tuning feature that enhances frequency ranges from 5 to 40 kHz with 114 decibels SPL sensitivity. You’ll get every detail that you want to hear which is important in music production.

Sony MDR7506 Professional Large Diaphragm Headphones

The MDR7506 from Sony is a high-quality, lightweight headphone that’s recommended for the broadcast industry and music industry. Inside is a 40mm PET diaphragm with neodymium magnets which matches the requirements of a variety of digital sources.

This Sony headphone is compact, easy to store, and is comfortable to use. It has a closed design with 10-20 kHz frequency response and 63 Ohms impedance. It comes with gold connectors and a convenient OFC cord to provide reliable and very stable signals.

Should we buy headphones with Harman tuning?

The Harman Curve is now known as the “best approximation” of what studio sound is like. If you want to hear and experience music and sounds as they are intended to be, then you should look for the best quality headphones with Harman Curve.

Again, you need to consider that not everyone may like the Harman Curve as we have different physiologies, likes, and dislikes. But if you are given the option to check out headphones with this amazing feature, try it out and see if the Harman Curve is worth it.

What other headphone response curves exist?       

If you want to try other response curve alternatives, check out free-field tunings and diffuse-field tunings.

Free-field response 

Free-field response was conceptualized by measuring the characteristic of a flat speaker placed inside an anechoic room. This type of room is needed to allow sound to be completely absorbed by the walls.

This type of response is not very popular as no one lives in an echo-free room. And, by outlining sound localization in human beings, it is easy to see that to mimic the natural sound, you must consider your environment very carefully.

Diffuse field response

Rather than an anechoic room, a reverberant room was used to develop a diffuse-field response. And instead of just one speaker, multiple speakers were placed around the doll. All these speakers were measured/tuned flat.

Sound moves from all the surfaces of the room and it's heard in all directions as well. This creates a more natural sound. Therefore, the diffuse field response is near-flat but with a more noticeable treble.

And because of providing a more natural sound, a diffuse field curve is used in more headphone models like the AKG 240DF, Etymotic Research ER4 headphone series, and the Beyerdynamic DT 880 Pro headphones.


Here are the most frequently asked questions and their corresponding answers to the Harman Curve

  • What is the Harman sound signature?
    The Harman Target Response Curve is quite similar to the balanced sound signature. You can modify the response to create a more natural sound. Professionals and audiophiles can hear an improvement in treble and bass which some people may find too unrealistic. 
  • What is Harman Tuning?
    Harman tuning is another term for the Harman Target Curve. It is a measurement of a specific frequency response designed for headphones.  This is completely different from speaker frequency response as headphones are designed differently from speakers even if both are audio output devices.

  • What is a neutral sound?
    A neutral sound signature is exactly what it is. It is a neutral sound with levels that are not enhanced for all ranges. The sound is the faithful reproduction of the original sound. Meanwhile, reference headphones are types of headphones that are tuned to make a neutral sound. Reference headphones are used to record, remaster sounds and for professional studio recordings.

  • What is a bright and dark sound?
    Dark sounds are sounds with a low volume of upper partials compared to lower partials while a bright sound has more upper partials compared to lower partials.  

  • Is the Harman Curve flat?
    Based on a headphone frequency response graph, the Harman Curve approximates flat speakers inside a studio environment. Because of the reverberation of the sounds in a room, the output will not be neutral but will still represent the original sound or recording.

  • Do speakers make better headphones and vice versa?
    Speakers won’t make good headphones as headphones won’t make good speakers. These two audio devices are completely different and work differently as well and thus, you cannot use these alternatively.

  • How the Harman Curve was created?
    The Harman Curve was created by scientists by determining the characteristics in free and diffused fields. They found out that none of these were able to provide a natural listening environment and hence, the Harman Curve was identified.

  • How many Harman Curves are there?
    There are four Harman Curves, each with specific frequencies and characteristics.

  • When was the Harman Curve created?
    The Harman curve was discovered in 2012 by scientists headed by Sean Olive, an audio engineer.

Wrap Up 

The Harman Curve helps listeners appreciate the natural sound. It provides an optimal sound signature that most people prefer to listen to. In short, it is the closest representation of what headphones sound like inside an ideal environment. Learning about the Harman Curve lets you appreciate sounds better.

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