As far as I can remember, even some of the special-purpose-hardware based solution like you'd find in a pair of noise canceling headphones do better on periodic noises. Not needing to race the soundwave seems like it should make the latency problem much more forgiving.

And the most annoying noises tend to be periodic anyway.

I think you should give it a try... let us test it, if you can cancel out my air conditioner noise you'll be my favorite person...