Multi-spectral phase coherence
Multi-spectral phase coherence is a generalized cross-frequency coupling metric introduced by Yang and colleagues in 2016. MSPC can be used to quantify nonlinear phase coupling between a set of base frequencies and their harmonic/intermodulation frequencies. MSPC is a model-free method, which can provide a system description, including the order of the nonlinearity, the direction of interaction, the time delay in the system, and both harmonic and intermodulation coupling.
The MSPC is defined as:
where is the phase at frequency, is the weight of to a harmonic/intermodulation frequency ), and represents the average over realizations.
Bi-phase locking value, also called bi-phase coherence in the literature, is a special case of MSPC when,
The time-delay can be estimated from the phase lag when MSPC is computed between signals.
