radio noise static

Has anyone else experienced this? Back in Dec timeframe, was practicing in my instructor's C172 at RHV and we were hearing what sounded like a radio station or something similar bleeding over onto tower's freq. Fast forward to a few days ago, and I hear the same thing on my handheld in my...

What do you make of this? Popping static that is random, but occurs at a higher frequency in flight. It is not heard when a transmission is being received. It is not heard on a handheld. It is heard on both left and right seat ports. There is no audio panel. Michel radio in a Stinson. Both mags...