FuzzMeasure reports its delay based on the sample index of the peak of an impulse’s energy (which is calculated more accurately by using the Envelope Time Curve in version 3.2 and above.)
Because of the way FuzzMeasure captures its recordings, this delay is affected by the audio hardware, and the Mac’s built-in audio services.
To eliminate this delay, you can use FuzzMeasure’s Automatic Correction feature, which is located in the Audio Capture Settings window.
When checking the Automatic Correction box, you must ensure the following points are true:
There is a loopback cable hooked up between the indicated Playback and Record channels. Failure to attach this cable will result in unstable and incorrect measurements.
You are measuring with a single device selected for playback and record. Mixed device measurements are not currently advised or supported.
The Automatic Correction feature is able to work the hardware/software delays by correlating the two signals that have both passed through the audio system. The common system delay in both signals is eliminated, leaving only the signal’s transit time through the air, or the closed loop system under test.
