ABSTRACT
This work is part of a project in a quest of the origin of speech, and in particular aims to define possible speech prerequisites in the geometry, the musculature, and the control of the vocal tract. From classical bony landmarks of the head and jaw used in anthropology, we attempted to predict the geometric limits of the vocal tract for modern man and to apply these predictions to fossils, namely two famous Neandertal skulls: La Chapelle-aux-Saints and La Ferrassie. We defined the limits of the vocal tract by the lip extremities, pharyngeal wall, and glottis position, which are important for the prediction of the maximal acoustic space of the vocal tract. We developed a database of midsagittal X-ray images of 22 speakers uttering vowels. Then, we selected the optimal combination of the bony landmarks that predicts the vocal tract limits and yields the smallest prediction errors. A second database was constructed that included a diverse collection of 91 skulls from places spread over the world and displaying strongly diverse skull morphology. We measured, for all these modern skulls as well as for the two fossils, the bony landmarks used to predict the vocal tract limits in the first database. We found that the bony landmarks of the two fossil skulls are located near the border of the dispersion ellipses of the modern population sample. We conclude that we may predict what could have been the vocal tract limits and the hyoid bone position of the two Neandertal men.
