Gastvortrag von Dr. Ian Howard

Gastvortrag von Dr. Ian Howard (University of Plymouth, UK) zum Thema " Robotic actuation of a mechanical vocal tract " am 09.11.2017.

Ort: Barkhausenbau Raum S52

Zeit: 9.20 Uhr

Abstract: The construction of mechanical models of speech production has a long history. To realize vowel production these models essentially make use of tube-like sections with cross sectional areas that can be varied, thereby changing the tube’s acoustic properties. In this way, a glottal source applied at one end of the tube can be appropriately filtered. This gives rise to acoustic output with a format-like structure, thereby simulating the production of the different vowel qualities that are made by the human vocal apparatus.
Here we describe a robotic vocal apparatus incorporating articulators that are moved by motors under computer control. The vocal tract consists of a central mouth region with a 2-dimentional tongue, a lip section and a nasal cavity. Movement of the articulators changes the vocal tract cross-sectional area, and thereby its acoustic properties, thus providing a means to generate different vocalic sounds.
Numerical optimization in Matlab was used to design the mechanism, which was achieved by fitting its various dimensions to published articulatory data. The design was then manufactured using 3D printing technology. Using voiced sound excitation, currently realized by means of a compression driver, we present some examples of vowel and nasal sound production. We also provide a comparison of the acoustic outputs generated by the robotic apparatus with those achieved by a reference set of 3D printed tubes that exactly represent each of the published vowel cross-sectional areas.
Finally, we demonstrate that this apparatus can also generated different fricative sounds. This can be achieved if the articulators are first positioned to generate a point of partial closure of the vocal tract. Then when air is then blown into the vocal tract at its base, this results in air turbulence at the constriction, leading to the production of a fricative.
Overall this project demonstrates the potential of robotic speech production and also highlights issues that may not arise in purely software implementations.