Hi, I have ETF 5 and I want to make a waterfall plot for my low frequency response. Now I am pretty sure I have done it right but I just want to know how you do it as I am not convinced. I set up the hardware as the help file says to then ran 'normal transfer function' selected 'Low Frequency' and 'MLS' and clicked 'Start Test'. That all works but for one I thought MLS was meant to be lots of small sound blips? It sounds just the same as white noise to me! If the gaps are so small I can't even hear them then surely that isn't enough time to measure decay rate? I suppose it could measure the decay after the sound stops at the end, is this what it does? I can make it then show a waterfall plot of the test and it looks alright (very good I think!) but I just want to know if I am doing it right?! Also, when I do a frequency response test it show some large variations (you can see on the waterfall plot). I set my system up using CoolEdit to generate white noise and analyse the results and it does not show such large variations! It doesn't sound like it has the variations either, so I am unconvinced of ETF's frequency response as well. Am I doing it wrong? Why does CoolEdit show such very different results? ETF's results look more like CoolEdits when I have not averaged the results over the whole white noise recording sample. Is the waterfall okay? Is it a good result?! Thanks!