[en] A phenomenological model was developed which is suitable for the interpretation of in-core measurements in boiling water reactors. In the new model the spatial dependence of the steam velocity was also taken into consideration. According to the phenomenological model the neutron noise can be composed from a local and a global component. By means of this model it was proved that the correlation velocity measurement is possible through the occurence of the local component. An approximative expression for the thermal flux fluctuation is derived by solving the dual-group diffusion equation. A relatively simple method was given to determine the spatial dependence of the global noise component in the BWR-type reactors. The local component in the neutron noise is a new means for reactor noise analysis. A way for separating the two noise components is given. (P.J.)