After another Trader asked about finding vacuum leaks, I offered mine. I had so many ask after that, that I did a search online. This is what I found https://inspectusa.com/ultrasonic-le...20Shop%20Group
I THINK it may work, but I'm only guessing. If anyone tries it, please report so others know. The CDL leak detector I sold, I could put on the included head phones and dial it in, so I could hear a leak from 15-20' away. I had to quit walking, but from one spot it allowed me to hear vacuum leaks in 20-30' of tubing. Then I'd walk further and repeat. CDL no longer carries them, I just wonder if the link above might do similar.