The bass flute is built specifically for its low register, giving it its individual tone quality which differs from the C flute. Its bore is ideally an optimum size to enable the low notes to have maximum sonority. The C flute, in comparison, has a compromised bore size to ensure an even sound across the three registers. The larger bore of the bass flute means that there are fewer high harmonics in the sound, so the tone quality is less piercing in the high register than the C flute.
The bass flute is a naturally quiet instrument, which can be easily overpowered within an ensemble. An experienced player will have the ability to control the air flow enough to create a reasonably wide dynamic range, and unamplified solo playing should be entirely achievable. However, care must be taken to carefully balance ensemble writing, and not to overcrowd the bass flute's pitch range.
The following examples demonstrate the dynamic curve of the bass flute, dependent on non-linearities of the instrument and the ear. Chromatic scales in each octave are played mp and then f.
Dynamic curve of the bass flute
The bass flute uses more air than any other wind instrument (except for lower members of the flute family), which has obvious limitations in terms of sustaining a fortissimo dynamic. This must also be taken into consideration when scoring with other instruments. For example, a fortissimo marking on the piano would easily drown out a bass flute at the same written dynamic. The pitch range of the instrument also creates balancing problems within an ensemble. Conversely, the bass flute is capable of very quiet, controlled dynamics. This should be carefully notated to ensure that the player understands the sonority required and doesn't overcompensate to ensure the sound projects.
Dynamic range, and projection, on the bass flute is controlled predominantly by tone colour rather than actual dynamic. This means that a note played at the upper limits of its dynamic range may be made to project more by intensifying the tone colour. The same is true of quiet dynamics – altering the tone colour will increase or decrease the apparent projection of the note.
When reading dynamics for the bass flute, the player will naturally compensate to allow the composer to hear the sound at the required dynamic. Care must always be given to allow the player ample time to breathe during loud or physically demanding phrases; the amount of air required by the instrument can be considerable, and this can easily result in fatigue.
Dynamic range of the bass flute