The Modal distribution is a time-frequency distribution specifically designed to model the quasi-harmonic, multi-sinusoidal, nature of music signals and belongs to the Cohen general class of time-frequency distributions. A streaming, object-oriented implementation of the Modal distribution is presented which forms the basis for designing other members of the Cohen class. Implementation of this routine in the C++ Sound Object Library provides a fully portable tool for time-frequency analysis across multiple platforms. The theoretical background to the Cohen general class is outlined followed by an explanation of the design and implementation of the Modal distribution in the SndObj library. Suggestions for future extensions to the new Modal class and its integration with the entire library are explored.