contraoctave
/ˈkɑntrəˌɑktɪv/
noun
- The lowest octave on a standard piano keyboard, typically from C0 to B0, with very deep bass notes.
- The organ's pedalboard includes notes in the contraoctave that rumble through the concert hall.
- Composers sometimes write for the contraoctave to create a dramatic, thunderous effect.
- He struggled to hear the contraoctave notes because they were so low and powerful.