Criticalidad, fenómenos de umbral y leyes lingüísticas en el habla

• Autores: Iván González Torre
• Directores de la Tesis: Bartolomé Luque Serrano (dir. tes.)
• Lectura: En la Universidad Politécnica de Madrid ( España ) en 2019
• Idioma: español
• Tribunal Calificador de la Tesis: Alvaro Corral Cano (presid.) , Javier Galeano Prieto (secret.) , Antoni Hernández Fernández (voc.) , Lucas Lacasa Saiz de Arce (voc.) , Hugo Ariel Navarrete Hurtado (voc.)
• Enlaces
  • Tesis en acceso abierto en: Archivo Digital UPM
• Resumen

  • Linguistic laws constitute one of the cornerstones, quantitatively measurable, of modern cognitive sciences and linguistics, and have been intensively researched during last century, mainly in written corpora. The conclusions reached from the study of statistical patterns of language are therefore, biased by the segmentation used, and characteristics such as the variability on the energy and duration of linguistic units are lost in the uniformity of the written transcription. In this thesis we examine whether linguistic laws hold with respect to the physical manifestations of linguistic units in segmented speech, and later, using a lexical independent segmentation method, we recover those equivalent statistical patterns at timescales even below the phonemic level, where cognitive process does not operate. Using well-known corporas, we first verify that acoustically transcribed durations of linguistic units at several scales comply with a Log-Normal distribution, and we quantitatively justify this observation using a stochastic generative model that only assumes lognormalty in the lower scale. Then, we find that classical linguistic laws appear stronger when using physical units than in their symbolic counterpart, supporting the hypothesis that statistical laws in language have a physical origin. We show that Herdan-Heaps law has to hold the same exponent regarding of the units of study, we propose for the first time a precise mathematical formulation of Zipf’s law of abbreviation, which we show to be connected to optimal compression principles in information theory and a mathematical derivation of Menzerath-Altmann’s law which also highlights an additional regime where the law is inverted. Finally, we apply the threshold method to the speech signal, without the need of a segmentation, recovering linguistic laws at infraphonemic levels and showing more evidences that the speech may be produced by a system operating close to a critical point. These methods support the idea that linguistic laws found in written corpora may be, at least in part, a byproduct of dynamics that emerge from non-cognitive levels and, in any case, it pave the way for new com parative studies in animal communication or the analysis of signals of unknown code.