Measuring source-tract interaction from speech

The objective of our study is to define and measure source-tract interaction using the speech signal. Numerous researchers have conjectured that the subglottal, glottal, and supraglottal portions of our own speech production mechanism may interact, affecting the quality of our voice. Several methods for incorporating the effects of source-tract interaction into a synthetic speech model have been suggested. Speech synthesized with source-tract interaction sounds more natural than speech generated without such interaction. Can source-tract interaction be parameterized using the speech signal and incorporated into vocoders and speech synthesizers? Can this measurement be accomplished on a pitch period by pitch period basis?