I know many of you have restrictions when it comes to studio space. They can be whiney neighbors, budget, infrastructure, you name it. And I know a lot of people are asking about the possibility of mixing with headphones due to these obstacles. So, I’ll try to shed some light on this topic.

Here’s my verdict: It’s possible, not optimal. Not at all optimal. Here’s why:

Inaccurate measurements = inaccurate frequency response:

First of all, mixing with headphones means having a suitable pair of cans to mix, open-back, over-ear cans, with the flattest and most accurate frequency response. And even if the manufacturer states that the headphones exhibit flat frequency response, measurements for these devices is not precise, as the ear has yet to be perfectly replicated to actually measure the frequency response, rendering the manufacturer’s range inaccurate.[1] And for the open-back design, the advantages are that the driver will move freely, with less resistance, better representing frequencies, and the small amount of leakage due to the openness means that they might get closer in representing the stereo panorama as a speaker system than the closed-back design. Closed-back might aid in the perception of low frequencies but it just might be coloration.



So people trying to convince themselves that they can mix on earbuds or airpods have already failed. Case closed. This includes most of consumer-grade headphones, also, as they color the sound pretty noticeable, especially those “bass+” or “bass enhanced” headphones.

Elimination of natural acoustics interaction with the whole ear system:

The human ear is an incredible device that has evolved to aid us in echolocation. Each part of the ear, outer, mid, and inner, work jointly to help the brain assess the signals coming into it, so we can better locate a specific source. The ear perceives the reflections of a signal in space, as well as the delay of said signal between ears, and translates it to a precise location in the field. It needs acoustics to accurately translate sound. So, the natural acoustics of a speaker in the open that are needed for the correct perception of the stereo image and frequency content of the program are removed when the transducer is placed immediate to the ear. [3][1] Therefore, an an-echoic playback system such as headphones would prove itself unnatural. Such a small space, between the headphones and the ear, won’t allow for needed reverberation to exist.

Distortion of the soundstage or panorama:

Next, the panorama (or soundstage) is blurred. As the ‘stereo’ phenomenon takes advantage of the leakage of the signals from two free-standing, non-isolated speakers into one another acoustically, having both signals confined into each ear, blurs or skews the stereo perception, making it harder to set the panning on the program material, as well as perceive correctly the ambiance effects, meaning reverb and delay. Make an experiment:

Set up a session with a mono signal you can easily track as you pan it.

Monitor first through your speakers and start turning the pan pot in both directions. Notice how the signal moves smoothly throughout the panorama.

Now monitor through your headphones. Pay close attention as, now, the signal suddenly shifts, or “escapes” suddenly from the center to a hard-left or hard-right position. There’s a void between center and hard positions.

This is due to the lack of said acoustical leakage present in a speaker-based configuration. There’s also say about difficulties to locate the phantom center using headphones but, personally, I haven’t found it that hard.

Skewed perception of height:

Then, the height. On the basics of mixing, an important aspect of a good mix is the illusion of hearing high frequencies ‘above’ low frequencies, and to correctly work this to further define each element’s space in the soundstage. This is enhanced, also acoustically, by the common design of modern speakers. Most designs place the tweeter above the woofer by a small distance, this enhances the illusion by physically reproducing high-frequency signals by inches above the low-frequency signals source.

On headphones, the space is often reduced, and the tweeter is mostly on par with the subwoofer, if the distinction exists. This means it becomes harder to perceive and, therefore, manage the heights of the program material.

Inaccurate low-frequency content analysis:

Speaking of low frequencies, headphone mixing will impair the critical listening of these. Big drivers are needed to accurately reproduce bass. Small speakers on headphones can’t vibrate with enough force to move the particles in the dimensions required for a low frequency waves, as well as the distance between the transducer in the headphone to the ear won’t allow for a low-frequency wave to fully develop. An 80Hz wave requires 4.29m to complete a cycle. This distance proves, also, why far-field monitors (which usually contain the largest drivers) are at a greater distance from the listening point than near-fields. Even if these frequencies are perceived in the headphones, they won’t be felt, which is an important part for precisely analyzing low-frequency content. [2]

There are software filters that promise flat-response correction for certain models of headphones. I bought one and have been using it for over 5 months now. At first it was a positive quality change, and you can hear how the mids (in my case) dip in volume, giving the sound a more clear perception. The con of using this kind of filters, is that I started to notice distortion on the lower frequencies. Even with the bass boost turned down and levels not clipping, I could hear some harmonics introduced into the signal. Speaking with support, we determined that maybe the headphones couldn’t handle the correction, rendering the main principle of the software irrelevant. I mean, if the correction can’t be reproduced by the headphones, then why correct in the first place?



NOTE: As of the time of publication, I’m still working things out with the software manufacturer’s support team to figure out what might be wrong with the system.

Conclusion

There is still room for headphones in the mixing context. You can use them as another reference. There is material mixed explicitly for headphones in the media world. And, obviously, headphones are still better than a badly treated room.



Another fair use of the headphones is clean-up. They work as a magnifying glass for audio, used widely when prepping the material for mixing. Yet you can overprocess and overclean with these, ruining the material instead of improving it.

“I’d say mixing on headphones is good for mixing individual tracks but not for the overall mix, as it can sound cluttered. But it is good, when doing mixdown, to use headphones as another source, along with different speaker types.” Rob Reed, producer. http://bluebeckrecords.weebly.com

There are INCREDIBLE headphones made for critical listening, but these rake in a huge buck, so they might still be far-off from many of us. Not mentioning the ADC and amps they need. But, sometimes, with these advanced models, all this theory might become a bit irrelevant. Yet, there are many engineers who still swear by doing critical listening in loudspeaker systems thanks to the benefits they bring.

Through the reasons supporting monitoring on speakers, one is that they closely resemble final listening conditions. But in this era of laptops, cellphones, and airbuds, listening on big speaker systems at home is going second place in our everyday lives. So we might need to reconsider our monitoring rules. But I don’t think it will happen soon.

And, finally, in my humble opinion, NO, I wouldn’t recommend doing the critical listening and finishing on headphones. But options are scarce in the monitoring environment world, and if you ABSOLUTELY need them, as a last resource, well, then go use them.

“Mixing on Headphones can help you get past a lot of acoustic treatment hurdles that one may face in a home studio. You can use the headphones to tell you what sounds best for your track when you mix and compare to hear what frequencies sound good and bad in your room” Jared Esposito, engineer. https://www.audioengineproductions.com

Just don’t think you’re hearing things better than your mixing engineer, sitting in his fully-fledged studio. Even then, your engineers probably have a better ear than you, so don’t try to argue that much with them.

References:

[1] Toole, F. E. (1984). The Acoustics and Psychoacoustics of Headphones. Conference Paper, 1–24. Retrieved from http://www.aes.org/tmpFiles/elib/20190910/11657.pdf

[2] King, R., Leonard, B., & Sikora, G. (2011). The Effects of Monitoring Systems on Balance Preference: A comparative study of mixing on headphones versus loudspeakers. Conference Paper, 1–7. Retrieved from http://www.aes.org/tmpFiles/elib/20190910/16091.pdf

[3] Everest, F. A. (2001). Master Handbook of Acoustics (4th. ed.). McGraw-Hill.





