Recent studies have indicated changes in the glottal excitation source characteristics apart from vocal tract resonances due to tongue tip trilling. In this paper we study the significance of changing vocal tract system and the associated glottal excitation source characteristics due to trilling, from perception point of view. These studies are made by generating speech signal by either retaining the features of the vocal tract system or of the glottal excitation source of trill sounds. Experiments are conducted to understand the perceptual significance of the excitation source characteristics on production of different trill sounds. Speech sounds of long trill and approximant pair, and apical trills produced by four different places of articulation are considered. Features of the vocal tract system are extracted using linear prediction analysis, and those of the source by zero frequency filtering.

Index Terms: glottal excitation source, trill synthesis, zero frequency filtering, apical trills, tongue tip trilling