Another great article on 6 Ways to Avoid Ear Fatigue while Mixing

Ty

85 dB SPL (C weighted) will sound quite a bit louder with pink noise compared to music itself. So I prefer to set the overall SPL with music, not noise.  One does not listen to noise generally.
 
85 to some may sound fine compared to others. They say that at 85 dB SPL the ear approaches the most even response. (note approaches! it is never flat) I have never really got the concept of only using 85 in large room. To my mind the room size should not matter too much. 85 is 85 arriving at your ears, room size or not.  I guess though that pumping 85 into a smaller room may tend to inject more energy into a smaller room compared to a much larger room. Which can be problematic for some smaller rooms.
 
The best way to keep an eye on SPL levels in your room is with a permanent SPL meter setup roughly in the sweet spot and telling you all the time how loud things are there.  Overtime with a long mix your SPL levels can creep up because your ears are getting tired and shutting down slowly.  It does keep you honest. 
 
Some around here are saying they cannot monitor at 85 and they are monitoring much lower e.g. 75 dB. This will give you inaccurate picture of what you are hearing.  At lower SPL levels your ears are less sensitive to low and high end which then may make you push these a little more which is also not good either.  You also need to check at loud volumes too e.g. 95 and 105 dB.  That reveals other stuff such as bass, kick and reverbs etc.. 

batsbrew
i don't know many people who casually listen to music at 85 db.
very few.

 
Are you saying they are listening louder or softer? I would be inclined to say much louder. 85 dB is not loud. I feel it is quite a nice level actually. Certainly in the morning after a good nights sleep it does sound louder compared to the end of the day. 

Even when I have my SPL meter set for 85 dB that usually only represents the loudest portions. Often it is more like 80 to 83 dB most of the time.  

yea, i sit about 32" away from my monitors, in the apex of the equilateral triangle,
and 85 db is painful!!
 
i usually do a 'loud' session up front, get basic levels,
then continue to mix at very comfy levels, near the end,
i have another 'loud' session, and look for sticky outy things.....
 

Great info guys!!!  Thanks Jeff.

I change the volume all the time when I'm mixing. I feel it helps give you a broad oversight of your mix, and is important because at the end of the day, people are going to be listening to your mix at all volumes! As Jeff says, if something is sticking out too much that will be far more obvious at low volumes, but it's also easier to hear what compression settings are doing at low volumes. I find this especially with mix bus compression - if you've gotten the settings wrong or are applying too much, this becomes especially apparent when you listen to it quietly. 
 
I also find it important to check on headphones now and then too. If you have a good pair of headphones that go down to 20Hz and you've flattened them with something like Sonarworks, they help in checking the bass, especially if your room isn't perfect. And since a huge proportion of people ONLY listen to music on headphones these days (especially kids), making sure your mix sounds good through them is very important. Personally I'm not a huge fan of how music sounds on headphones and I have a very low threshold past which I think "ew that sounds horrible" through them. A really well done pro mix, however, sounds great through both speakers and headphones. Things can end up sounding claustrophobic and cluttered through cans if you're not careful, and many a time I've gotten things sounding very open and airy through the speakers only to find that they didn't sound that way through headphones at all, especially if the low mids are too much.