  Using spatio-temporal spectra we show direct evidence of excitation of
magnetosonic and Alfv\'en waves in three-dimensional compressible
magnetohydrodynamic turbulence at small Mach numbers. For the plasma pressure
dominated regime, or high $\beta$ regime (with $\beta$ the ratio between fluid
and magnetic pressure), and for the magnetic pressure dominated regime, or low
$\beta$ regime, we study magnetic field fluctuations parallel and perpendicular
to a guide magnetic field $\textbf{B}_0$. In the low $\beta$ case we find
excitation of compressible and incompressible fluctuations, with a transfer of
energy towards Alfv\'enic modes and to a lesser extent towards magnetosonic
modes. In particular, we find signatures of the presence of fast magnetosonic
waves in a scenario compatible with that of weak turbulence. In the high
$\beta$ case, fast and slow magnetosonic waves are present, with no clear trace
of Alfv\'en waves, and a significant part of the energy is carried by
two-dimensional turbulent eddies.
