  The search of the phonon structure at the above-gap energies was carried out
for $d^{2}V/dI^{2}(V)$ spectra of MgB$_{2}$ point contacts with a normal metal.
The two-band model is assumed not only for the gap structure in
$dV/dI(V)$-characteristics, but also for phonons in $d^{2}V/dI^{2}(V)$
point-contact spectra, with up to the maximum lattice vibration energy. Since
the current is carried mostly by charges of 3D-band, whereas the strong
electron-phonon interaction occurs in 2D-band, we observe the phonon
peculiarities due to ''proximity'' effect in {\it k}-space, which depends on
the variation of interband coupling through the elastic scattering.
