From speech corpus to intonation corpus: clustering phrase pitch contours of Lithuanian

This paper presents our research in preparation to compile a Lithuanian intonation corpus. The main objective of this research was to discover characteristic patterns of Lithuanian intonation through clustering of pitch contours of intermediate intonation phrases. The paper covers the set of procedures that were used to extend an ordinary speech corpus to make it suitable for intonation analysis. The process of intonation analysis included pitch extraction, pitch normalization, estimation of the representative frequency of a syllable, measurement of an inter-phrase similarity, k-means phrase clustering, and visualisation of clustering results. These computational procedures were applied to 23 hours of read speech containing 41417 phrases. The clustering results revealed some interesting intonation patterns of Lithuanian that could be related to the well known linguistic-prosodic phenomena. Language-independence is an important feature of computational procedures covered by this paper. If speech waveforms and the knowledge of phone and phrase boundaries are given, these procedures can be used for the analysis of intonation of other languages.