No doubt this will get moved to the TECHNIQES forum butt,...
 
'Tis a thread in the TECHNIQUES forum about monitoring levels and using pink noise.
 
Yesterday I purchased the December issue of Sound On Sound (still on news-stands) and find an article about mixing using pink noise.
 
Part of the reason to do so is to emulate the general background noise level of most environments in which we usually hear music. Especially in cars, and trains,... This noise is heard even when we are using ear-buds, and headphones.
 
I read about this many years ago in conjunction with the recommendation to place any noise makers (fans, computers,...) behind the mixing desk, dead center, so as not to skew the perception of frequencies heard by both ears.
 
About the same time as reading these ideas, I purchase a copy of "Sonar 3 Mixing and Mastering" written by THE CRAIG, and much to my happiness I find his exploration of this idea on page 369.
 
THE CRAIG rules. History is his playground!
 
(This issue also has THE CRAIG's article about pumping reverb using Sonitus plugs.)

Glad you liked the technique. It was first published in Keyboard magazine, I think it was over 10 years ago so it was never posted on the Keyboard magazine site. However, I did revise the article and posted the revised version on Harmony Central for those who want details.
 
There was a forum thread on HC where someone said how well it worked, and he found -20 dB was about right for the noise level...that's a common level for what I use, but sometimes I boost the level a bit.
 
When the article was originally published people thought I was crazy, but those who have used it do find that it works.

I got onto it a few years ago with the concept of having a soft purring fan or heater in your control room at the same time as mixing. It has a similar noise vibe to it as pink noise down low.
 
Just remember it is not for every mix and if you want very subtle changes in volume of detailed parts down low etc it may get in the way and make it harder to mix.
 
But for keeping things present in a lot of styles it works very well too.  The other side of the coin is listening to your mix down at a low SPL level in mono through one Auratone type speaker.  It also reveals a lot of similar information such as many parts being present and being heard.  It is also good for making things stand out too much or leap out. 
 
I think the more things you can try while you are mixing the better.  They each have their individual take on information about your mix.
 

I have two main sources of noise going on - a large air cleaner in the room, and a nearby bathroom with a noisy heating pipe. I'll generally do everything I can to reduce this noise when mixing - turning the fan off, and closing the bathroom door - but sometimes I'll work on a mix with the fan left on and have noticed that I'm working harder to make everything sound clear. I always thought that ultimately it was a no-no and that if I'm every working on something serious (i.e. non-hobby) then I should make sure everything is turned off while mixing. But maybe I'll leave the fan on sometimes. 

Just make sure any noise you introduce is broader across the frequency spectrum in nature.  More frequency specific sounds may influence you in the wrong way. 
 
I think the concept of introducing pink noise into your main mix buss is not hard to do either.  In hardware form into your monitoring system  (I have a Behringer DSP2496 for live PA use that generates pink noise) or inside your DAW as a signal generator sound on a track.  That way you have got precise level control too.  This discussion got me investigating the capabilities of my digital mixer internal oscillator. Turns out it has a variety of waveforms and extensive routing options.  I can add pink noise in easily within the digital mixer concept.
 
It is also very nice to be able to turn it off too and have a very quiet monitoring background. I am lucky in that I do and I like working in that environment a lot.  It is essential at times.
 
The noise can also hide any tinnitus problems if you have very specific high frequencies for example that may be ringing in your ear.  If you experience this, you will find listening to white or pink noise for a few minutes relieves it and it goes away.  (for a while, I think the brain gets confused with the noise and it forgets which is the annoying high feedback frequency eg it gets buried)  So introducing low level amounts of pink noise may be good for this too.
 
 
 

If you're interested in giving this technique a try, I found a pretty easy way to do it.  Use the link and download the small pink noise Test Tone file (.wav format) from http://www.audiocheck.net/soundtestsaudiotesttones_index.php .  You can import that wave file into a project that you are mixing and loop the playback (or create a groove clip and copy it to the end of the project).  I'm still on the fence about when or how often to use the technique, but I do use it occasionally.  It seems to yield some good results..........Give it a whack if you like!