A theoretical model of turbulent mixing layer receptivity to localized energy deposition is proposed. The triple decomposition is utilized for the flow field. The model is based on the biorthogonal eigenfunction expansion for the coherent (phase average) part of the perturbations. The mixing layer flows in the considered examples of two-dimensional perturbations are more susceptible to higher frequencies. However, the low frequencies are more unstable, and the overall effect depends on receptivity and downstream amplification of the perturbations. Nonparallel flow effects are included into consideration. It was found that the there is a dominant frequency in a wave packet of perturbations that depends on the downstream observation point location.