Magnets do indeed impact the operation of the PM.
Security devices should be passed through quickly, otherwise they can interfere with your PM.
As for speakers, they operate on the principle of magnetism/electricity causing vibration. They too impact PMs.
Several intersections causing symptoms of magnetic field:
it could be there are antennas in the vicinity, security devices, or other interfering electro-magnetic fields.
When you feel the disruption, get away from the offending souce, for the good of your heart.