Both air leakage and throttling have a common cause and phenomenon. Both are turbulence caused by sharp changes in the gas channel which result in the generation of sound waves. Therefore, from the acoustic point of view, their characteristics are relatively similar.
In practice, adjusting the dynamic range to see if the acoustic image is distributed along the pipeline indicates that there is a throttling phenomenon. When the leakage point is near the throttling pipe, the location of the leakage point can be confirmed by approaching the leakage point or changing the angle for multi-angle imaging. Using the focus function aids the pinpointing of the leak.