Bass clarinet
The low variant of the clarinet in B♭.
What it means
The bass clarinet is the low member of the clarinet family. It is pitched in B♭ and sounds a major ninth lower than it is notated in the treble clef: a written C′ thus sounds as B♭. It is built with a curved crook and an upturned bell, so that the long tube stays manageable. Like all clarinets it has a single reed and overblows at the twelfth, which is why it has a very large range. Many instruments reach, by means of additional keys, down to the sounding A or lower.
Musical use
Firmly anchored in the orchestra since the nineteenth century, the bass clarinet unites two properties: in the low register it can sound dark, soft and almost menacing, in the high register by contrast lean and songful. It thus takes on both bass functions in the woodwind group and expressive solo passages. Composers use its ability to speak very quietly for transitions and changes of colour. In the twentieth century it additionally became an important instrument of chamber music, of improvisation and of jazz. From the contrabass clarinet it differs in range: that one sounds an octave lower still.
Performance practice
Reckon with distinctly more air than on the B♭ clarinet and with a more sluggish response in the low range; support the breath and keep the embouchure loose, so that low notes do not crack. The intonation of the highest register is sensitive and demands checking through embouchure and the mental image of the sound. Watch for a secure stance: most instruments are played with a peg or strap, and a wrongly set height spoils the embouchure and hand position. Check the many keys and pads regularly, because even small leaks make the low register unplayable. Warm the instrument up well before playing.
Remember that the notation is not uniform: alongside the usual writing in the treble clef, older, especially French, scores have a notation in the bass clef in which the transposition turns out differently. Check this before you learn a part. In the orchestra the task frequently lies between bassoon and clarinet; listen to both sides and adjust articulation and vibrato. For quiet entries in the low range a reed is needed that speaks securely even in piano.