You can largerly hear past room reflections at high frequencies, but the reflections will still create an uneven frequency response that causes audible colorations. At higher frequencies some of this will even sound as nonlinear distortion, such as an ear bleeding tweeter. The sorts of correction that was presented above can lead to a very pleasant sounding top – airy and clear, but at the same time without the usual artifacts that produces listening fatigue.

Overcorrection can be many things. In my book it is what you get when you correct a cancellation so much that you get temporal overshoots of several dB, and the infamous “hollow sound” when someone tries to equalize the bass to perfection. This can be avoided by using an approach such as Farina’s AQT or similar. Using such an approach will not lead to overcorrection, but will help avoid it.

In any case, it is important to use a tool that enables a high degree of manual voicing to get the best possible result. Measurements and correction templates can get you in the ball park but the fine tuning has to be done by ear.

Back then, still today, we worked exclusively in real time. We didn’t apply a sine sweep to the room, get an impulse response and then generate a synthetic test signal (Figure 6) put headphones on and listen to it. That was way too much work, too slow and cost too much in analog. Mainly back then we were all pretty much into instant gratification (joke). In the mid 80s our first distribution of that test signal was on a 3 minute loop cassette. We just played the tape and listened to it. Then you could record what you heard, make changes in the room and record what you now heard. You could easily recognize what improvement, if any, you made, and you could listen to the A/B test any time you wanted to. Life was simple back then, before DSP.

Here’s what you want to do. Just listen to the original version, the electronic MATT test over headphones and then power up your system and listen to the signal again. You will be immediately astounded about what it reveals to you about your room’s ability to play music. You don’t have to look at graphs that are meaningless, just listen. It is amazing and a little humbling to hear your room actually gargling note sequences instead of yodeling them.

Norm, you had some experience with the MATT testing we did back in the early days when you were working for Bruce Brisson at MIT on our 2C3D listening room project. And just think, you didn’t even recognize that this test is derived from the MATT test. That’s how convoluted this Italian offshoot of the MATT test has become. Let me quote Angelo Farina, the author of an AES paper delivered in 2001 where AQT was first presented. In his introduction he states that his present work is “an evolution of the MATT test…” There you go…

Glad to hear that you like it.