Originally Posted by jim19611961
I thought I would elaborate on my take of the waterfall in an interpretational way.
The top slice represents your FR basically. Each slice below that equates to the "echo" of that response in the time domain modified by the room response.
In a perfect world, the FR would be a strait horizontal line representing the same sound pressure for every frequency. Each additional slice would also be a flat horizontal line as you move further in time from the direct response. So in a perfect world, 100ms (for instance) after the direct response, the sound pressure level for each frequency would still be constant, but some measure of -X db down. Such a scenario would imply a room that is perfectly flat across the frequency domain as you move further from the direct response in the time domain. This is the ideal.
Now, what we see in our waterfalls is a asymmetrical FR followed by a asymmetrical room response. This represents itself as the direct response (FR) in the top or first slice that has asymmetries (not perfectly flat), followed (in time) by a room response that treats the decay of frequencies differently as you move in the time domain.
Thanks Jim. I tried to explain how things should (ideally) be even through the time domain, but the above quote explains this better.
Here is a graph that shows what is being described.
Shamelessly stolen from here
. <<<< Good read!
Originally Posted by cfraser
And I do agree that treatments that may
only show small changes in the graphs can have a much larger audible effect. Those more experienced would recognize this though, but most of us here only have one room to "practice" on.
For instance, the old DIY bass traps I mentioned before, compromisingly installed in this room, do not show "large" changes in the LF waterfalls. In fact, in some areas they show what to a newbie looks worse in some ways. But it sounds a lot better and clearer because they're doing something up at the higher end of the bass region, and into the vocal area/mids. Actually, they make a very large diff to me, beyond what the graphs would suggest. i.e. if somebody tried to sell me the traps "on paper", I'd have said no thanks...going to be more careful now. Fun!
Some (most actually) things only come with experience. Measurement graphs can be difficult to read. For the simple fact that a measurement graph might be weighting an area with greater or lesser emphasis then what our auditory system does.
I personally prefer to make changes and then listen to those changes first
. After listening to the system, I then take a measurement of the system. This way, if the measurement does not translate to what I am expecting, I have not clouded my listening experience. In this way I feel I can more clearly interpret the measurement based on my listening experience, rather then trying to interpret my listening experience based on a measurement graph that I might not be understanding completely.
Originally Posted by djbluemax1
It strikes me that some of the waterfall anomalies can be more easily seen depending on the rotated angle of view (and I've seen people with different viewing angles with different waterfalls), but I've never figured out how to do that
Indeed. I don't want to take away from the importance of having a base line set of standards that people follow when posting their results, but it's important to understand that some things might be better represented with different settings.
I have a tendency to always be playing around with waterfall settings, and I should include a standard waterfall with my custom waterfalls to make it easier for people to see how I am displaying my results.Edited by Audionut11 - 12/27/13 at 8:56pm