  Goldstone modes emerge associated with spontaneous breakdown of the
continuous symmetry in the two-channel Kondo lattice, which describes strongly
correlated f-electron systems with a non-Kramers doublet at each site. This
paper derives the spectra of these collective modes by the equation of motion
method together with the random phase approximation. The diagonal composite
order breaks the SU(2) channel symmetry, and the symmetry-restoring collective
mode couples with magnetic field. On the other hand, the off-diagonal or
superconducting composite order breaks the gauge symmetry of conduction
electrons, and the collective mode couples with charge excitations near the
zone boundary. At half-filling of the conduction bands, the spectra of these
two modes become identical by a shift of the momentum, owing to the SO(5)
symmetry of the system. The velocity of each Goldstone mode involves not only
the Fermi velocity of conduction electrons but amplitude of the mean field as a
multiplying factor. Detection of the Goldstone mode should provide a way to
identify the composite order parameter.
