The Harman Curve is a frequency response target curve for headphones.
In the audio world, the development of the Harman Curve came into existence after conducting extensive research on the type of sound preferred by headphone users.
It intends to create a naturally balanced and accurate sound fit to ensure a smooth and consistent listening experience across different types of music, podcasts, and other audio content.
Additionally, this curve targets good clarity, detail, and imaging of sound.
The Harman Response Curve exhibits a relatively flat frequency response in the sub-bass range of 20Hz to 60Hz, followed by a gentle elevation in the mid-bass region spanning around 60Hz to 200 Hz.
The curve maintains a consistent level over the low mid (250 to 500 Hz) and mid-range (500 Hz to 2 kHz) frequencies, followed by a gradual roll-off in the high frequencies above 10 kHz.
It has become a widely recognized standard in the headphone industry, with prominent manufacturers employing it as a reference target to develop and evaluate their products.
However, it is pertinent to mention that it is not the only available option; different organizations may have their personalized sound preferences based on the subjective listening experiences of their customer bases.
Benefits of the Harman Response Curve
AKG’s K371 loosely follows the Harman Target
Being a standard for various audio productions, this curve has numerous implications, including:
Well Balanced Sound
The Harman Curve targets natural sound reproduction, meaning that different frequency ranges are represented in a way so they are perceived equally and harmoniously by the listener.
Precise Representation
The audio is developed without introducing any considerable levels of colouration or distortion, thus minimizing response deviations that may adversely impact the listener’s perception of the original recording.
Compatibility
The curve is well-suited and inclusive of a wide range of music genres, ensuring unbiased and untainted audio reproduction with impressive preservation of distinct music types.
Potential for Standardization
Being employed as a common reference target by many industry players, it can lead to greater standardization and consistency, and enable useful comparisons across different headphone models and brands.
Limitations of The Harman Response Curve
The K371 with iFi’s Diablo
While the Harman Response Curve has gained popularity in the audio industry, there are certain limitations to consider:
Subjectivity
This curve is based on subjective user preferences and may not necessarily demonstrate an objectively “ideal” frequency response.
Perception of sound can vary according to consumer tastes and hearing abilities.
Narrow Sample Size
Moreover, the Harman Curve is a product of the research conducted on a relatively small and specific demographic of listeners, primarily from North America.
There is a possibility of different sound preferences and perceptions among people of other regions; the “pleasing audio experience” cannot be generalized to the global population.
Limited Scope of Application
The Harman Response was designed specifically for headphones and so may not be applicable to other audio systems, such as speakers and microphones, as they possess different operating features.
Alternatives of The Harman Response Curve
Some manufacturers may opt for other alternatives depending on their priorities and engineering goals. Some of the alternatives are as follows:
Free Field (FF)
The Free Field Equalization response curve is designed to replicate the sound field experienced in a free field, where sound is radiated directly from the front with minimal reflections.
It typically has a flatter midrange and a gradual fading trend in the bass and treble compared to the Harman curve.
Diffuse Field (DF)
This alternative is a by-product of research that suggests that the ideal headphone response should mimic the sound field experienced in a diffuse environment.
The Diffuse Field curve is based on the frequency response of sound in a diffuse field, such as a concert hall.
This curve is designed to provide a raw and natural sound similar to what one would hear in a live performance.
Unlike the Harman Curve, the Diffuse Field curve does not emphasize the bass frequencies.
User Targeted Curves
Some companies conduct specialized studies to determine listener preferences across diverse demographics and music genres.
These studies can result in alternative target curves, specifically tailored to certain content types, which can be used to achieve optimal results.
User Adjustable Curves
The audio systems and software applications that allow users to customize the frequency according to their preferences are characterized by user-adjustable curves.
This flexibility makes the customers feel valued, as they can define their own experience, rather than being limited to the standard target curves.
Evolution of The Harman Response Curve
Graph courtesy of Crinacle
The Harman Response Curve is not a static concept but has continued to evolve over time.
The ongoing evolution of the curve involves continuous research and refinement to enhance its accuracy and applicability.
Harman International, along with other researchers and organizations in the audio industry, collects data to further understand the “pleasing listening experience”.
Harman International collaborates with research institutions, universities, and other partners to conduct studies and share results.
This contributes to a deeper understanding of both the subjective and scientific aspects of the frequency response characteristics.
Furthermore, there is an increasing trend in individualization driven by factors such as age, hearing abilities, and genre preferences.
The development and use of the Harman Response Curve have spurred further research on sound quality evaluation and perception.
Researchers have explored other aspects besides frequency, such as spatial attributes, distortion, dynamics, and timbre, to gain a more comprehensive understanding of sound phenomena.
- Related: What is Timbre?
Recently, there has been an attempt to address one of the criticisms of the Harman Curve that it does not account for the effects of long-term listening.
Researchers have investigated the impact of varying frequency curves on listener fatigue and discomfort, thus paving the way towards better-than-ever headphone tuning and potentially transforming the audio industry.
The curve is further being used as a reference for training machine learning and artificial intelligence algorithms to improve the accuracy of electronic optimization.
Final Words
To recap, the Harman Response Curve offers several benefits in the realm of audio engineering and headphone design.
Its data-driven tuning approach provides a frequency response that aligns with the preferences of a majority of listeners.
However, the curve is based on subjective research and cannot be regarded as an all-encompassing model.
As it continues to evolve and there are other options available, considering your sound preferences and making an informed decision likely constitute the best way.
