Doing this a task like this should be pretty straight forward if you already have the wav files, or can get them off the web (I've seen sites that make chords available in the .wav format). Taking accurate response times using DirectRT is no problem although you would normally take the RT from the onset of the sound files rather than the end. You can start measuring from the end but that would require you to find out exactly how long your music (chord) files are in milliseconds. A number of sound applications can tell you that (e.g., the freeware program Audacity). But all that said, yes, DirectRT should work well for you and it comes with many samples that you can use as a starting point. We'll also be happy to help you get rolling if you run into any trouble or difficulties.