  The ghost note is a natural note which can be played exclusively on bass
brass instruments with a predominantly-expanding bore profile such as tubas,
euphoniums or saxhorns. It stands between the pedal note-the lowest natural
note playable, or first regime-and the instrument's second regime. However, if
the interval between the pedal note and the second regime remains close to an
octave regardless of the instrument, the interval between the pedal note and
the ghost note vary from a minor third to a perfect fourth. References about
this note are very scarce, and it is not commonly known among tuba players.This
study shows that an elementary brass model describing the player coupled to the
instrument is capable of bringing both the ghost and the pedal note to light.
Here, we adopt a dynamical systems point of view and perform a bifurcation
analysis using a software of numerical continuation. The numerical results
provided in terms of frequency intervals between pedal note and ghost note are
compared with frequency intervals experimentally inferred from recordings of
seven different types of tuba, each of them being played by two professional
tuba players.
