To understand why mixing on headphones is difficult we need to understand what happens to sound in a real room environment.
In a real room sound reflects around the room boundaries or any physical objects in that room so when a sound leaves a speaker it doesn't just go to the listening position it just bounces around everywhere and those reflections
changes the perception of the sound at the listening position.
Simplified example of sound reflections in a control room.
On headphones that doesn't happen the sound is literally directly coming out of the drivers of the headphones and directly into your ear.
This means that you are getting absolutely zero reflections from the acoustic environment and this makes listening on headphones a completely different experience to listening on speakers.
To be able to make good mixing decisions the acoustic environment has to sound good and a lot of people have acoustic environments that are sub-optimal and a bad environment is going to really impact the quality of your mix.
If you can’t trust your monitors and room treatment you are likely to have to check the mix in numerous different environments and speakers to see how it translates to different listening systems.
A control room of an acoustically designed studio is going to have a very low overall reverb time, which is usually in the region of 0.2-0.3 seconds.
This reverb time is also going to be as flat across all frequencies as possible; meaning that certain frequencies aren't going to ring on for longer than others they're all going to be within the ballpark of each other. In less well-treated rooms this is not the case you will usually find that bass frequencies,
in particular, will ring out for a lot longer than the higher frequencies and that can become a problem.
Another common problem with headphones, and perhaps the more
important problem to solve is crosstalk between your ears.
This is the primary reason that most mixers struggle to work on headphones.
Let’s explain the problem.
When you're wearing a set of headphones, if something is panned to an extreme it only comes out of the one speaker. For example, if a sound is panned completely to the left it only comes out of the left speaker. With headphones on that means it's only going to be coming into one of your ears.
However, when you're listening on speakers that's not the case.
When the sound comes out of the left speaker, it will arrive at the left ear first because of the shorter physical distance, but it will still arrive at the right ear.
Our ears can localise the direction of a sound based on this property, this is called Inter-Aural Time Difference (ITD).
The sound from the left speaker will still arrive at the right ear but later. It will also be slightly lower in level; this property is called Inter-Aural Intensity Difference (IID).
Simplified example of crosstalk between speakers
Finally, the tonality will have changed too, because to arrive at the right ear it has to travel through/around your face or off a wall to get to there. As you can tell, this is a much more complicated scenario than wearing headphones.
I know what you are thinking, how does this sound?
Headphones often sound unnaturally wide, lack low-frequency body and often the sounds in the phantom centre (the elements which come out of both speakers at equal level) seem “less solid”.
Remember, what lives in the phantom centre of a stereo-image: Drums, Bass, Lead vocals i.e. the most important parts of your mix. If you are mixing with the most important elements compromised it is no wonder mixing is harder on headphones.
The way in each ear can localise a sounds position can be represented by a mathematical function called a Head Related Transfer Function (HRTF), each persons transfer functions (one for each ear) are unique based on a number of factors including, ear size, distance between ears, head circumference and many, many more.
When mixing exclusively on headphones I find that it often sounds extremely different on speakers. However, the reserve is not true, mixes made on speakers usually translates better to headphones.
If you don’t have an acoustic environment you can trust or have to exclusively mix on headphones then you have a disadvantage. The traditional method of solving this is to just get so accustomed to the differences that you could image what it sounds like on speakers.
This requires a lot of trial-and-error and is obviously imperfect.
These are the primary problems that Waves – Abbey Road Studio 3 plug-in solves.
It not only gives you some “virtual room ambience” (and one that is modelled on one of the best control rooms in the world).
It also solves the crosstalk problem, has head tracking features and models the Head Related Transfer Function of an average person.
If you would like to check out the plug-in, here is a link to its sales page (full disclosure this is an affiliate link):
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