Assertion: percussion instrument's pitch | /r/HasProperty | hum tone
Facets:
value: an octave below
type: OTHER
Source sentences:
text: "The bell produces a secondary pitch (f') which lies outside that 'inharmonic series though it is clearly audible when the bell is struck, 'to curiously thrilling and disturbing effect.'"The strike tone is middle C , the hum tone an octave below.