SynRTA is a freeware soundcard-based audio frequency response analyzer designed for easy optimization of loudspeaker and listening room responses. SynRTA makes response plots from 12Hz to 20,000Hz and at frequency resolutions of 1/6th, 1/12th, 1/24th, or 1/48th octave.
Like common "RTA" analyzers, SynRTA uses "Pink Noise"-like signals. To use it, play a signal through your system, pick up the sound with a microphone connected to your soundcard, and watch the response curve on your computer. A nice thing about using noise is that you can just play it on a CD without having to wire a computer to your sound system. A not-so-nice thing is that noise is ...noisy. With an RTA, you usually have to wait enough time to average the response to see what it settles down to.
SynRTA's operation is keyed and synchronized to specific test signals that sound like pink noise (but aren't really noise at all). This lets SynRTA response graphs appear stable and very repeatable at each graph update . SynRTA response graphs don't need to "settle". It makes finding the best position for speakers and adjusting equalizers simple and efficient.
If you've ever used an RTA and pink noise to try to measure your system, you know what a pain it can be. Seeing the curve at the higher frequencies is pretty easy and reasonably fast, but the lows seem to take forever to settle down to a comprehensible shape. You probably ended up not wanting to try too many things with your system, life is just too short.
Or if you've worked with a measuring setup using chirps, MLS, impulses, or tonebursts, each measurement is fast. But in that case, timing is everything. The microphone end needs to know exactly when and what the sound-playing end is doing. The test signal isn't the same all the time, so you need to catch it just right. And that usually means tying in the computer to the sound system, usually with long cables stretched across the room. Then, you usually have to go through separate recording and processing operations, messing with the computer when you want to be trying things in your room or with your sound system.
SynRTA is designed to be easy like an RTA and quick like a synchronous system. And it's free. What more do you want?
A lot of audiophiles and home theater owners spend large amounts of cash on gear, in an attempt to improve sound quality. Usually, though, the placement of speakers, subwoofers, and listening chairs and the presence or absence of absorbtive materials will have far more effect on sound quality than will equipment purchases. Often the room effects at low frequencies are so bad that just working with positions isn't enough. If you use a parametric equalizer to help further tame low frequency room effects, SynRTA will allow you to watch and compensate for room effects and standing waves in near real time.