This paper explores the possibility and extent of non-uniqueness in the acoustic-to-articulatory inversion of speech, from a statistical point of view. It proposes a technique to estimate the non-uniqueness, based on finding peaks in the conditional probability function of the articulatory space. The paper corroborates the existence of non-uniqueness in a statistical sense, especially in stop consonants, nasals and fricatives. The relationship between the importance of the articulator position and non-uniqueness at each instance is also explored.
Bibliographic reference. Ananthakrishnan, G. / Neiberg, D. / Engwall, Olov (2009): "In search of non-uniqueness in the acoustic-to-articulatory mapping", In INTERSPEECH-2009, 2799-2802.