Every iAudioInterface is factory calibrated, and shipped with calibration constants for line input trim (3 ranges), microphone trim (2 ranges), and output trim. To calibrate iAudioInterface to your device, you simply enter these constants into the appropriate fields in AudioTools. By doing this, you will be in “rough” calibration (within a few dB).
Since the input sensitivity varies from model to model, and to a lesser degree from device to device, you will need to trim your device to get to “fine” calibration. We have included typical trim values, by device, for all current iPhone* and iPod touch models. So as a first step, enter the appropriate constant for your device. To get to absolute calibration, you will need access to one of the following:
— A microphone calibrator
— A calibrated dB level meter
— A calibrated generator
Then, go to any of the calibration screens, and adjust the trim field until the AudioTools reading matches the calibrated reading. Once you have trimmed your device using any single calibration field, all of the other values will be accurate.