Now that you have ascertained the source, why not just call them up and ask
them? They would probably appreciate knowing that the neighborhood can hear
them, they are probably not aware. And, if it turns out to be a surveillance
operation, you may have an opportunity to own your own bugging device. It would
bring good money on E-Bay. Finders keepers. Companies that vend those devices
to law-enforcement such as Westinghouse/AID in Ft. Lauderdale Florida usually
start around $1,000.00.