REW (Room EQ Wizard)

Free desktop software for measuring room acoustics, loudspeakers, subwoofers and audio devices. It measures frequency response and distortion using swept sine signals, provides a real-time analyser, signal generator, sound level meter, oscilloscope, spectral decay and waterfall plots, impulse and step response analysis, reverberation time measurement, clarity parameters, distortion analysis, phase and group delay, impedance measurement, and equaliser configuration for a range of hardware DSPs. A paid Pro upgrade adds multi-input capture and Speech Transmission Index calculation.