Every law-enforcement vehicle, every vehicle authorized to be equipped with warning lights pursuant to §§ 46.2-1022 and 46.2-1023 shall be equipped with a siren, exhaust whistle, or air horn designed to give automatically intermittent signals. Such devices shall be of types not prohibited by the Superintendent.
Sirens or exhaust whistles on emergency vehicles
Va. Code Ann. § 46.2-1061, under Chapter 10. Motor Vehicle and Equipment Safety..
Va. Code Ann. § 46.2-1061