The Impulse response module for AudioTools or standalone application provides an easy way to capture an IR audio file on iOS devices, and also calculates the most-needed metrics from the data. Impulse Response is an iOS port of a powerful mathematical model developed on desktop computers by Daniel Valente, Ph.D architectural acoustics, rensselaer polytechnic institute. In seconds, a complete set of measurements is made that describe the acoustic character of a room, or the response of a loudspeaker.

Impulse response on the iOS device will give you very good results, even with the built-in mic. Of course, you are limited to moderate SPL levels, and the lowest frequency bands will not be as accurate as when used with iAudioInterface2 or iTestMic, but impulse response will give you accurate reverb decay times and other measurements. You can record either an actual impulse, or a swept sine wave that the app will deconvolve into an impulse.