The two-time correlation function of the director fluctuations is calculated for a homeotropically aligned nematic cell in an external magnetic field. The anchoring strength, the splay-bend elastic constant are taken into account. An influence of the surface parameters on light -scattering data is discusses. It is shown, the ratio K-13/K-33 affect the frequency spectrum of the scattered light when the in-plane component of the scattering vector is equal to zero. A geometry of an experiment, that gives the frequency spectrum different from single Lorentzian, is offered.