Air leaks are common problems on production lines. There are a number of reasons why a loudspeaker enclosure might have an air leak and detecting leaks during final test can be challenging. Thankfully, Sound Check includes a couple of algorithms that, while not specifically designed to detect leaks, have an excellent track record of air leak detection.
Algorithms for Air Leak Detection
Loose Particle: The loose particle algorithm, as its name implies, was designed to detect the presence of loose particles in a loudspeaker. The algorithm produces a time based envelope having a magnitude proportional to the intensity of the loose particle "rattle" in the recorded time waveform. Since air leaks have an acoustic characteristic similar to that of lose particles, the algorithm is able to detect the leak and create a loose particle envelope which can be passed through a limits step to create a Pass/Fail verdict during the production test.
The Loose Particle algorithm is available in all of SoundCheck's Analysis algorithms.
Rub & Buzz: Rub & Buzz analysis looks for the presence of high order harmonics (H10 and above) in the recorded time waveform and since air leaks produce a lot of high frequencies relative to the fundamental, Rub & Buzz does a good job of detecting leaks.
The Rub & Buzz algorithm can be enabled in Analysis on the Distortion tab in the HarmonicTrak and Time Selective Response (TSR) algorithms.
Air Leak Detection Example Sequence
Attached (link below) is an example sequence in SoundCheck 16 format. The sequence recalls two recorded time waveforms, one of a system with an air leak and one without, and performs Loose Particle and Rub & Buzz analysis on both. The results are shown on multiple graphs along with examples of how Pass/Fail limits can be applied.
The user is encouraged to explore how changing the analysis settings effects the results and, if your SoundCheck license includes the Signal Generator option, you can even listen to the Recorded Time Waveforms and Loose Particle Waveforms.
Run the sequence directly from the folder as the waveform recall step uses a relative filepath.