Assertion: modern sousaphone | /r/AtLocation | the key of bb♭
Facets:
Source sentences:
text: Most modern sousaphones are made in the key of BB♭ (Low B Flat) and like tubas (which are commonly made in pitches of BB♭, CC, EE♭, and F) the instrument's part is written in "concert pitch", not transposed by key for a specific instrument.