I thought I'd start this thread regarding mixing and fatigue... and while I wrote this to target newer engineers, it contains decent info for us veterans as well.

We work on a mix, we hit rewind, we play. Hit rewind, play. Then we stop in the middle because we hear something that sticks out, something that bothers us. We might even put that section into a loop mode so that we can sweep frequencies or check for anomalies. Sometimes they really are there, sometimes they are a fiction of our imagination and over-worked aural senses. Any way you add it up, the result is that we hear these tracks over and over and over again, and in doing so, we begin to lose objectivity. Fatigue happens to all of us at some point. Of course, there are monitors out there that are inherently harsh, ( Yamaha NS10's) and the room you are mixing in matters big time as well. Still, this fatigue happens to audio cats on all levels and in home studios and pro environments alike. We're all human, and have the same limitations, which, yes, will vary from person to person, but in the end, we are all subject to at some point.

And this is just mixing. This doesn't include the fact that if we also happened to be the recording engineer as well, we've already heard it a gazillion times before we even begin to mix.

Here are some suggestions as to how you can work more efficiently.

1. Mixing Volume. It will vary, but the standard accepted reference volume is 80-85db*. However, this level can sound louder than that, if you are in a room that hasn't been treated. The actual level remains the same, but we don't fatigue out as fast if the room is smooth in terms of frequency response. You should check your mixes at a variety of levels, doing so will give you an indication of how certain instruments will sit in the mix. Mixing at a lower volumes isn't bad. In fact, you can go for longer periods of time. But, you should occasionally check your mix at hotter levels as well. It also greatly depends on the style of music you are mixing.
* This is the level accepted by many as a standard. On a personal note, I can tell you that 85db is too hot of a level for me to mix for any serious length of time. I generally mix at an average level of around 75db, and check my mix occasionally at hotter levels.

2. Keep an original copy of the project. Save it as such. Label it "Song Name original copy/date". This is the project that holds all the tracks before you started mixing. Don't change this project... Ever. LOL.
Have a working copy of the project. Make a copy of the project, this will be your working copy. This is where you add processing, effects, alter balances and EQ. Title this "Song Name working copy/date".

3. Store your tracks. Not just your project. Export the individual tracks to folder on a backup drive. Having a folder with the exported tracks serves a couple of purposes. The first is that you have a safety backup of all the tracks, should your program or platform crash and burn. The second - yet no less important reason - is that you will have these raw tracks to use should you decide to take them to another facility and import them into another platform... PT, Sonar, Cubase, Samplitude, MixBus, Studio One, etc. There are quite a few engineers - myself included, who use one platform to track with and use another to mix with. If you have the time and patience, export all the original, unprocessed tracks in the original copy to it's own folder. Pay close attention during your export process as to what kind of file it is. In Sonar, you have the choice of how you want to export these tracks in regard to format: wav is the current standard, although many DAW platforms also allow exporting files as aiff, mp3, orbis, SDII, etc. You also have the choice of Mono, Stereo or Split/Dual Mono. Make sure you export these tracks as their original format. Don't export stereo tracks as mono, or vice versa, unless you have a reason to.

4. Take a break. The quicker you give yourself a break at the earliest signs of trouble, the less time it will take you to recover. The more time you spend making changes or trying to fix things which result in bad sounding tracks and mixes, the longer it will take you to recover. In many cases, I've been able to resume in less than an hour. However, in some cases, if I'm really stubborn and keep plowing away at it, it's sometimes been a matter of days before I can come back to the mix with a fresh sense of what the song needs... or, just as importantly, what it doesn't. At the earliest signs of fatigue, the first onset, when you start making changes that either don't need to be made, or that result in sounds that are worse than before you started changing things, walk away.

5. Use other sources. Many engineers - even studio vterans, will have music that they reference their own mixes against. It could be any song, any style that sounds fgood to you sonically. It might not even be a song you like as a song, but that you like as an example of a great mix. Another thing you can do is to use other ears to check your work. A pair of fresh ears, someone who hasn't heard the track hundreds of times and who can bring a sense of objectivity, can be very helpful... but this person should be someone you trust, someone who's mixes you've heard, and who has proven that they know what they're doing. I have three people whom I trust implicitly... one is audiokid from right here on this forum. Chris has helped me out many times by allowing me to send him mixes that he can listen to and critique for me. I trust his ears, and he's a pro at what he does. We also tend to like the same styles of music, which doesn't hurt, either.
Understand that you aren't looking for a musical critique. You are looking for a mix critique. Although, know that you could play the track for 4 different engineers and get 4 different opinions. Consider the source. If you have someone whose mixes you like, use them. One way to do this is to take one track/problem at a time.. "Can you listen to this vocal track for me? Something is bothering me and I can't put my finger on it." Even if you can put your finger on it, don't tell the other person. You don't want to plant anything in their head before they've heard it. Let them tell you what they think. They might come up with something you hadn't heard, or make a suggestion you hadn't considered.

6. Gear matters. It matters a lot. The nicer the gear you have, the more effective and efficient it is, and you spend far less time getting what you need when you are use a processor that actually does what it claims to. In terms of quality, professional caliber processors tend to do what they do very well.
Plugins , while convenient - and cheap - can often quicken the onset of aural fatigue, because you have to spend so much more time trying to make a plug sound like what it is supposed to be emulating, and the more time you spend, the quicker you burn out. If you are lucky enough to have a real LA2, dbx 165, or other real piece of pro caliber gear, you'll get the results you want, and you'll get them quicker. Plugs are just emulations, and often, very poor ones at that. Tap into a cheap LA2 plug/emulation, and you'll spend a lot more time trying to figure out why it doesn't sound the same as the real LA does.
Bottom line...The better your gear, the better your sound.

7. Limit your processing. Don't swamp your tracks with VST's. Every time you do, you are adding another source from which fidelity problems can occur: smeared image, phase issues, lack of definition and clarity, muddy bottom, brittle mids, sharp, glassy hi's. I'm not suggesting that you don't use plugs, I'm merely suggesting that you limit how much processing you use. Make sure that the tracks really do need the processor you are plugging into. Don't assume that every track will automatically need a compressor or EQ. Listen first! In many cases, instead of using a compressor plug, you can alter the volume envelope of the track instead. You can also tonally adjust instruments by working with mic placement. You'd be amazed at just how much sonic difference you can from a source by simply moving a microphone as little as an inch in any direction.

8. Know your tools. If you don't know what a compressor or limiter does, then why would you use one? Research these tools. If you don't know, find out what they are and what they do.
Simply this: If you find yourself jacking 100Hz through the roof on a flute track, then it's time to stop and study. The internet is filled with wonderful sources of education relative to audio recording. Take an online class. Berklee offers an online class for introduction to audio recording. and it's FREE.

https://www.coursera.org/course/musicproduction

9. Keep your ears clean. You don't need to do it every day, or even every week, but you should pay close attention to wax build-up inside your ears. This build up will absolutely effect your hearing, particularly with upper frequencies.

10. Your room matters. Having an accurate listening and mixing space is crucial. Beyond effecting your mixes, a bad sounding room can fatigue your ears much quicker than an environment that is easy to work in, in terms of sonics. If your room is accurate, you'll spend far less time at the console/DAW in front of your monitors. Less time spent mixing means less fatigue.

Most of the time, it all comes down to knowing when to quit for awhile. If you find yourself making things worse with your changes, then it's time to walk away. It may be for just an hour or so, sometimes much longer. Good Luck :)

d/