Assertion: western culture's music | /r/MadeOf | multiple keys
Facets:
value: often
type: TEMPORAL
Source sentences:
text: Classical music from the Romantic era (written from about 1820–1900) often contains multiple keys, as does jazz, especially Bebop jazz from the 1940s, in which the key or "home note" of a song may change every four bars or even every two bars.