Would you like to buy headphones? You need to know about the “Herman curve”

If you recently bought high-end headphones, you’re quite likely to come across what’s called a “Harman target curve” or just a “Harman curve.” You might have read a review that the headphones are tuned for your target, so they sound great. Or you might have seen an edgy comment suggesting headphones tuned to Harman’s curve.

But why are more manufacturers, audiophiles, and reviewers paying attention to the Herman curve?

There is a lot of science behind the sound of headphones, much of which is covered in our primer. Speaker measurementHowever, in some respects, headphones are even more complicated. This post is intended to be an introductory book for making more informed purchase decisions, rather than a complete guide to headphone measurement.

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Let’s dive.

What is the Herman curve?

The Harman curve is a science-backed headphone frequency response target.Created by Dr. Sean Olive and other researchers Herman Audio In the 2010s (Harman is owned by Samsung and includes headphone makers such as AKG and JBL), it’s the result of several studies trying to identify what makes great-sounding headphones.

Basically, the Herman curve seems to be the current best answer in science to the question “Which frequency response is most preferable for most people?”

It is worth noting that what people “like”, as seen in speaker frequency response measurements, is largely interchangeable with what people consider to be “neutral.” People simply tend to prefer what sounds most natural to them.

It should also be noted that there are several versions of the Herman curve. For example, the target depends on whether you’re talking about over-ear headphones or an in-ear monitor (IEM, also known as earphones). Also, through ongoing research, the goals have been slightly adjusted over the years.

What does the Herman curve look like?

This is the latest version of full size headphones (blue) and Harman Curve for IEM.

Herman target curve

The above does not apply only to “raw” headphone measurements that have not been specifically calibrated. This is also the response measured on the particular test gear used by Herman. Measurements made on other devices cannot be completely compared.

It doesn’t look flat at all! Why does it sound neutral?

There is thorough evidence suggesting that speakers with a flat frequency response when measured in an anechoic chamber are preferred by listeners and perceived as neutral. So why is the target of Harman headphones so far from the flat line?

The first part of the answer is in our own body. When listening to speakers, or musical instruments or voices, much of the sound passes through the head and torso before reaching the eardrum. The sound from the left speaker passes through the nogin and the frequency response changes before it reaches the right ear.

Correct this sound Head related transfer function (HRTF). Our brain is smart and uses this sound modification to understand where the sound comes from.

The problem with headphones is that these frequency responses do not change when you bring them closer to your ears. The sound from the headphones directs your gaze directly to the ear canal. So instead, it’s up to the manufacturer to find a way to roughly emulate an HRTF with the frequency response of the headphones. Headphones with a truly flat frequency response will sound terribly dull.

However, it is not enough to reproduce the sound of the speakers in the anechoic chamber with headphones. After all, no one (except scientists) listens to speakers in an anechoic chamber. Therefore, the second part of the Herman curve duplicates some of the characteristics of the speaker response in the room.

When a good speaker is placed in the room, its sound will be slightly tilted (details). why In us Speaker measurement guide) There are many basses and few trebles. Speakers are generally perceived as neutral, but the brain uses the tilt of the room to position the sound coming out of the speakers so that it is present in the room.

Herman scientists believe that music is generally mixed for listening to room speakers, so ideal headphones try to reproduce the sound of a room’s excellent speakers, resulting in large bass bumps in the Harman curve. I did.

The final curve was determined by responses from study participants, but the basic principles are the same. The best headphones are the ones that sound like the best speakers.

But we all have different tastes in music! How can I handle all with one frequency response?

This is the problem: you’re probably not much more special than you think.

According to Harman’s research, as with speakers, the vast majority of people have similar preferences in headphones, and those preferences can be largely predicted by frequency response data. In one study, researchers found that measurements could predict over-ear and on-ear headphone preferences with an astonishing 86% accuracy. For in-ear monitors, the model was even more accurate, at 91%.

One study (Olive et al., 2014) tested listeners from different countries, age groups, and experience levels. Participants scored differently for each headphone, but trained listeners, for example, tended to be more critical. Ranking The same is true for headphones.

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