Based on Bernoulli statistics of bubble dynamics, a model of void Fraction fluctuations in two-phase Rows is introduced. The model is used to characterize changes of the intensity of void Fraction fluctuations at various two-phase Row regimes. i.e. bubbly, slug and annular flows. Depending on the applied frequency band, the behavior of the band-passed variance of void Fraction Fluctuations changes significantly. At high frequencies, the band-passed variance increases monotonously with increasing void fractions, while the variance over the whole frequency range has a prominent maximum. By performing model calculations, the relationship between microscopic two-phase Row parameters and macroscopic Row quantities has been analyzed.