the term "Standing Waves" comes from the original research, where single, static tones were used to demonstrate their existence. I don't think that the term is misleading if you are approaching this from a math or physics orientation, and an awful lot of musicians have that background - and vica-versa, but that's another tale!
There is a lot of research being done today in the area of digital signal processing to correct room anomalies. It ranges from the active devices mentioned by Bit to equally active arrays of microphones and loudspeakers to insanely narrow bandwidth filters. And all of them show some promise, and all of them cost orders of magnitude more than building a purpose built room<G>!
When you look at the current crop of room correction software tools (ARC, Genelec, etc) you need to really study what they can do, or more to the point, what they can't do. Otherwise you are fooling yourself, which may, or may not be an issue. If you like the way the room sounds after the correction then go for it. If you don't, then you need a little elbow grease.
And the thing is, and a lot of people ignore this at their own peril, the same is true of geometry, absorption, diffusion, and reflection. Even withing the narrow spectrum of diffusion we have multiple ways to diffuse sound, QRDs, Polys, etc, and they too have their strengths and limits.
Here's a silly example... one of the things we need in a critical listening space is the absence of noise, and sometimes we have the complimentary requirement to keep the music in the space, so that it does not become noise elsewhere. So we build an enclosure that isolates the space from the rest of the world.
What happens to the energy then? Yes, it stays in the room, so a well isolated space has MORE problems with standing waves than a poorly isolated space. OK, maybe not so silly after all?
So what is a person who wishes to have a reliable, accurate (define accurate!) critical listening system to do?
Step 1: figure out what you really need. Isolation, accurate frequency response - and how low do you need it to go, accurate transient response, all of the above? Doesn't matter, just figure out what you need.
Step 2: Study! Find out what techniques address your requirements. Read case studies (especially, read about the Tom Hidley designed studio at Masterfonics in Nashville!!!) In general isolation is achieved through mass, and the rest is addressed through some combination of geometry, absorption, diffusion, and reflection.
Step 3: Find out what your specific limitations are. Room size, room dimensions, construction, geometry, and fixtures are often the biggest obstacle since most of us have to work with an existing space. OK, so work within that framework!
Step 4: Build something... not quite anything, but you get the drift, try something!
Now 40 years ago I could spend time in studios, some well designed, some not so much. Over time I developed a sense of what worked for me. As an example, as good as modern monitors have become, I miss the Altec 604 family of monitors. That's rock and roll, that's fun!
Sadly it is much more difficult for folks to get that sense today. First, there are fewer studios, second, those studios that are still around are busy, and may not welcome visitors.
Which brings us to software designed to correct room problems...
if you are curious, and you can afford it, give it a try! I don't know that any one of them is better (or worse) than the others, so just give it a spin. Figure out what it can, and can not do for you, in your space.
Just be careful not to believe the hype! None of them will fix room resonance or bad reflections. No matter what the developer claims...