Reduced interference distributions: biological applications and interpretations

Time-frequency (TF) signal analysis has recently experienced a slow awakening followed by an accelerating development of interest. This paper discusses a specific concept applied to TF signal analysis, the reduced interference distribution (RID) approach. The RID approach is aimed at achieving high-resolution TF distributions within Cohen's class with much reduced cross term or interference activity which often disappoints users of the well-known Wigner distribution (WD). The RID concept is briefly developed and then a number of examples from biomedical and biological settings are discussed. These discussions attempt to accomplish the dual task of illustrating the usefulness of the approach in investigating these problems and to teach one how to interpret the results obtained as well-the art of using the approach. RID results are contrasted with the WD and the spectrogram, another well-known tool. Some of the new and exciting TF approaches that deviate from the RID concept, but provide good results and interesting theoretical frameworks, are also brought in as appropriate.