Went out to record one of the Modulators in downtown Newport. I wasn't sure if they'd silent test or not, but turns out they don't: They do alternate wail! Skip to 1:30 for the Modulator. Sirens heard in the background include: 4/5 port Thunderbolt 1000T, chopper level 7 Thunderbolt 1000, possibly other Thunderbolts, some T-128's, an E-Class or two, and 2001(s).