Electroglottography  provides a noninvasive perspective on vocal fold behaviour without influences from speech articulation. The Lx signal (the changes of the laryngeal conductance) contains not only reliable information about fundamental frequency, but also more detailed information about the voice quality, which may be used to differentiate modes of vocal fold activity. An attempt to use the Lx signals in classification of various phonation types is described, using not only the temporal structure of signal, but also description of the Lx signal shape. The Lx signal was represented using a wide set of parameters and then classified for four phonation types using the rough sets approach  and statistical discriminant analysis. The classification rules and subsets of the most important parameters were also determined, showing the importance of both, time and shape, parameters for the Lx signal classification.
Bibliographic reference. Marasek, Krzysztof (1995): "An attempt to classify LX signals", In EUROSPEECH-1995, 1729-1732.