Disk bottomed pans are more prone to noise in my induction experience when compared to clad pans.
Also if you've used the pans a lot for years, some slight warping can develop. This can make your pan rock against the cooktop, even very slightly. With the cycling of the magnetic field, it can make the pan vibrate against the cooktop.
It's possible its the cooktop, but it's most likely disk bottom pans/slight warps.