Extremely useful
This is THE app to have if you are in the field of acoustics at all. Using Dayton imm-6, calibration file and an acoustical calibrator with this app, Im within a dB (across the spectrum 1/3 octave) of my reference desktop measurement system which uses a calibrated Earthworks M30. No, the described setup is not lab grade, but it is good enough for the majority of use cases. Using the ipad camera connection kit, I run the art dual pre to a real measurement mic for results on par with desktop Smaart. Note that this app has an add on for Smaart that is $49.99. It is single channel only but has proven extremely valuable. Audio tools does have its own add on module for dual channel measurements if you have the need. The spl meter modules using the imm-6 is reliable to about 110dB; beyond that it would be better to use a connection kit, USB sound card and decent measurement mic. There are a ton of tools and calculators included. The add ins are expensive but the base set alone is worth the asking price if you are really in the field. Read their website and watch the videos to get an idea of what this app can do.
Jf4828 about
AudioTools - dB, Sound & Audio, v6.6