Assertion: contralto's role | /r/HasProperty | categorized into voice types
Facets:
value: commonly
type: TEMPORAL
value: in opera
type: LOCATION
Source sentences:
text: In opera, the tessitura, vocal weight, and timbre of voices, and the roles they sing, are commonly categorized into voice types, often called fächer ( sg. fach, from German Fach or Stimmfach, "vocal category").