Thanks for the question, Sarah. Yes, auditory stimuli are frequently used to cancel unwanted trigger sounds. I personally love to listen to music through noise canceling earbuds and it works awesome. (I describe the headphones more fully in my 1/19/13 post.) For me, listening to the music works much better than my earplugs because they completely block out triggers - as well as other distracting sounds. Although my earplugs are quite good, they still allow me to hear conversations and other outside sounds. Listening to music isn't the only type of auditory stimuli that is used to cope with triggers though...
When I was first diagnosed with misophonia, the doctor allowed me to test a pair of noise generators (I don't remember if they were considered white noise, pink noise, or brown noise generators...) as a means to help cope with the multitude of triggers that bothered me. The noise generators looked like little hearing aid earpieces with a tiny filament that sticks inside the ear and created a low hissing sound. (They were similar to what I found on this earplug website, but a lot less clunky.) From what I understand about how they functioned, the hissing creates a sound buffer that covers up the majority, but not all, of triggering sounds. The doctor described the trigger sounds pictorally, like a wave diagram, and the noise generator supposedly creates a higher sound baseline that only allows the tips of the offending sound waves to pass through. (See diagram below.) By doing that, the wearer can still hear normally through but the triggers are not as noticeable above the white noise.
In the end though, I decided not to get the devices for two reasons: 1) They were pretty expensive (her "discounted rate" was about $900/ear, and the $1,800 to get devices for both ears would not be covered by my insurance. I was not ready for that kind of out-of-pocket hit to my wallet especially when my $5 earplugs - for a pack of 50 pair - were giving me similar results), and 2) Sounds only constitute a fraction of my misophonia triggers. Granted, sounds are the largest component of my triggers, but they are followed very closely by numerous visual triggers and tactile ones as well. I didn't want to spend so much money on devices that only address part of my misophonia triggers. I'd rather use the money towards my search for doctors that are willing to look at my condition medically as a whole and might be able to help me find a more comprehensive treatment/solution.
But that's just me... I'm sure there are other misophonia sufferers who don't have the diversity of senses affected by triggers; and for those people, these noise generating devices may be a great way to function without using earplugs to dull the overall sense of hearing. I think it's up to the individual to find what works best for him/her situation.