Assertion: heavy metal's sound | /r/CapableOf | employ orchestras and opera singers
Facets:
value: sometimes
type: TEMPORAL
Source sentences:
text: Many power metal bands such as America's Kamelot, Finnish groups Nightwish, Stratovarius and Sonata Arctica, Italy's Rhapsody of Fire, and Russia's Catharsis feature a keyboard-based "symphonic" sound, sometimes employing orchestras and opera singers.