If you happen to’ve shopped for high-end headphones not too long ago, there’s a reasonably good probability you’ve come throughout one thing known as the ‘Harman goal curve,’ or maybe simply the ‘Harman curve.’ Perhaps you learn a evaluation that stated a pair of headphones sound superb as a result of they’ve been tuned to stated goal. Or maybe you noticed an edgy remark suggesting headphones tuned to the Harman curve suck.
However why precisely are extra producers, audiophiles, and reviewers listening to the Harman curve?
There may be loads of science behind the acoustics of headphones, a lot of it coated in our primer on speaker measurements, however in some methods, headphones are much more complicated. This submit isn’t meant to be an exhaustive information to headphone measurements, however somewhat a primer that will help you make a extra educated buying resolution.
Let’s dive in.
What the heck is the Harman curve?
The Harman curve is a science-backed frequency response goal for headphones. It was created by Dr. Sean Olive and different researchers at Harman Audio within the 2010s (Harman is owned by Samsung and contains headphone makers like AKG and JBL) and is the results of a number of research attempting to pinpoint what makes a great-sounding headphone.
Mainly, the Harman curve seems to be science’s present finest reply to the query: “what frequency response is essentially the most most well-liked for the most individuals?”
It’s price noting that, as seen with frequency response measurements for audio system, what folks ‘desire’ is basically interchangeable with what folks take into account to be ‘impartial.’ Individuals merely have a tendency to love what sounds most pure to them.
I also needs to notice that there are a number of variations of the Harman curve; the goal adjustments relying on whether or not we’re speaking about over-ear headphones or in-ear screens(IEMs, AKA earbuds), for instance. And once more, the goal has been tweaked barely over time with ongoing analysis.
What does the Harman Curve appear to be?
That is the newest model of the Harman curve for full-size headphones (blue) and IEMs:
Not that the above solely applies to ‘uncooked’ headphone measurements with none explicit calibration utilized. It’s additionally the response as measured with the precise testing gear Harman makes use of – measurements created with different units should not totally comparable.
That doesn’t look flat in any respect! How may that probably sound impartial?
There may be exhaustive proof to recommend audio system which have a flat frequency response when measured in an anechoic chamber are most well-liked by listeners and perceived to be impartial. So why is the Harman goal for headphones so removed from a flat line?
The primary a part of the reply lies with our personal our bodies. When listening to audio system — or, , devices and voices — a lot of the sound passes by means of your head and torso earlier than arriving at your eardrums. Sound coming from the left speaker will go by means of your noggin, inflicting its frequency response will change earlier than it arrives at your proper ear.
We name this modification of sound the head-related transfer function (HRTF). Our brains, intelligent issues they’re, use this modification of sound with the intention to work out the place sound is coming from.
The issue with headphones is that their proximity to your ear doesn’t enable for these frequency response adjustments to occur. Sounds leaving your headphones have a direct line of sight to your ear canals. So as an alternative, it’s as much as producers to discover a option to roughly emulate the HRTF of their headphones’ frequency response. Headphones with a really flat frequency response will sound awfully boring.
However we additionally don’t simply need headphones to copy the sound of audio system in an anechoic room. No person listens to audio system in an anechoic chamber, in any case (effectively, apart from scientists). So the second a part of the Harman curve is replicating a number of the traits of an in-room speaker response.
When a great speaker is positioned in a room, its sound develops a slight tilt, (extra on why in our information to speaker measurements) with extra bass and fewer treble. The speaker is mostly nonetheless perceived as impartial, however your mind makes use of that room tilt to assist place the sounds leaving the speaker as current in your room.
The scientists at Harman figured that since music is mostly combined to be listened to on audio system in a room, then ideally suited headphones would attempt to replicate the sound of excellent audio system in a room, resulting in a few of that large bass bump within the Harman curve.
The ultimate curve was decided by responses from examine individuals, however the basic precept stays the identical: the perfect headphones are those that sound essentially the most like the perfect audio system.
However all of us have completely different tastes in music! How can one frequency response match all?
Right here’s the factor: you’re most likely rather a lot much less particular than you suppose.
The Harman analysis discovered that, as with audio system, the overwhelming majority of individuals have comparable tastes in headphones, and that choice can largely be predicted by frequency response knowledge. In a single examine, researchers discovered that measurements may predict the choice for over-ear and on-ear headphones to a exceptional 86 % accuracy. For in-ear screens, the mannequin was much more correct, at 91 %.
One examine (Olive et al., 2014) examined listeners in several international locations, age teams, and expertise ranges. Though individuals gave completely different particular person scores to completely different headphones — skilled listeners tended to be extra crucial, for example — they ranked headphones very equally.
All that being stated, person-to-person variations do exist. Older examine individuals as an entire tended to desire brighter headphones on account of listening to loss, whereas girls tended to desire a bit much less treble vitality. Some customers most well-liked kind of bass. Completely different particular recordings would possibly profit from barely completely different headphones, on account of one thing known as the circle of confusion. And all of us have completely different heads and our bodies with considerably completely different HRTFs, making the good headphone for a person listener arduous to foretell.
However these variations in choice tended to be a lot subtler than audiophiles usually declare. Listeners tended to desire Harman curve-tuned headphones regardless of particular person variations, so it seems the general contour of the Harman curve stays largely preferential over different tuning strategies. A lot of the variation in choice may very well be accounted for if headphones enable for fast bass and treble changes, enabling them to be versatile for a good wider number of listeners and genres.
So is frequency response the one factor that issues?
There are actually different issues that may have an effect on your listening expertise.
If a headphone has extreme distortion or an intense resonance at a sure frequency, it won’t sound nice. It normally takes a large quantity of distortion for listeners to poorly price a headphone, nevertheless it does occur.
Typically a headphone would possibly observe the Harman curve actually carefully however have a stray peak that you just discover actually annoying. And the Harman curve doesn’t totally account for the spatial qualities of headphones, which differ relying on their dimension and design. Two headphones can have comparable tonal steadiness, for example, whereas demonstrating completely different spatial qualities.
Pure sound high quality apart, there are actually different essential qualities to contemplate. Some folks received’t purchase headphones with out noise-canceling, for example, and plenty of listeners take into account consolation to be paramount. Different headphones won’t get loud sufficient in your makes use of, and nonetheless others might need an excessive amount of latency in your tastes. These quality-of-life traits are sometimes simply as essential as sound high quality.
Nonetheless, in relation to tonal steadiness, frequency response is king.
So ought to I solely purchase Harman headphones?
In fact not.
Though the goal curve because it’s at the moment identified was developed by Harman, its headphones are removed from the one ones to comply with the goal. Some headphone firms independently arrived at frequency responses that carefully observe the Harman goal earlier than it was developed, whereas others have since tweaked their headphones to match the curve.
Likewise, not all of Harman’s headphones match the curve, particularly a number of the firms’ older fashions.
I’ve heard Haman curve-tuned headphones and I didn’t like them! Now what?
Firstly, you must enable your self a minimum of a bit time to adapt; should you’ve been listening to poorly tuned headphones for a very long time, your ears might have a little bit of acclimating to do.
But when that doesn’t assist, that’s superb too. The Harman curve was by no means purported to be the end-all-be-all for sound high quality. As a substitute, it offers a place to begin backed by science, which is an enormous step ahead from the haphazard tuning many headphones had a few many years in the past. Though most listeners are comparable of their tastes, it’s potential the optimum headphone for you would possibly differ considerably from the Harman goal.
Nonetheless, I’d nonetheless argue it’s essential for any headphone fanatic to have expertise with a headphone tuned to the Harman curve as a result of it’s a helpful reference.
The Harman curve is more and more turning into an business commonplace, so it offers some extent of perspective for headphones that deviate from their sound. Say a evaluation claims headphone A has much less bass than headphone B, the latter of which follows the Harman curve. When you have expertise with Harman-esque headphones, you’ll have a stronger understanding of the reviewer’s impressions and the way they may relate to your individual tastes.
Headphone acoustics is a discipline of constant analysis, particularly as binaural audio, Dolby Atmos, and different spatial audio strategies turn into extra common. We might discover that the best headphone response continues to evolve over the subsequent decade; some firms wish to tailor headphones to the person’s listening to, for example.
However within the meantime, shopping for a pair of headphones tuned to the Harman curve doesn’t assure you’ll like them, nevertheless it’s merely your most secure guess for getting one thing you’ll truly get pleasure from.
