Sound is produced according to the same principles as on the clarinet in Bb:
To play, the reed is placed on the lower lip, which is pressed against the lower teeth while the upper teeth grip the mouthpiece on the closed side. When blowing the clarinet, the reed is controlled and set in motion by means of lip pressure, air pressure and the points of contact between the reed and the lower lip. The vibrating reed sends little puffs of air into the air column inside the instrument, thus causing the air column to vibrate.
The notes of the clarinet’s compass are produced either by opening or closing the appropriate tone hole or key with a particular finger or fingering combination. On the whole, the fingering is the same as on the clarinet in Bb, the sound is an octave deeper.
The Bb clarinet has a compass down to a written E3 (sounding D3). On the modern bass clarinet this range is extended downward thanks to four additional keys, so that a sounding Db3, C3, B2 and Bb2 can be played. In 20th century literature the lowest notes are asked for time and again, especially in Russian music, e.g., in Sergei Prokofiev’s Romeo and Juliet.
Unlike the higher-pitched clarinets, the bass clarinet (and the basset horn) have two speaker keys. The second speaker key means that the tone hole for the written Bb3 need not be used for overblowing or opened for all the high notes above the written B4.
The bass clarinet is generally played in the sitting position with the spike resting on the floor. If the clarinetist plays standing up it is held on a strap, like the saxophone.