Estimating the Degree of Retroflexion based on Ultrasound Data

Abstract

Retroflex consonants are common in languages of India and South Asia in general. Asia in general, yet differ across languages in the degree of the tongue tip of retraction. Understanding language-particular differences across languages in the degree of retroflexion is important for successful treatment and remediation of speech language disorders involving retroflex sounds. The objective of this paper is to propose and evaluate a method of estimating the degree of the tongue tip retraction based on ultrasound data. Measurements of the retroflexion angle were made based on our previously published data from 10 normal adult Kannada speakers producing retroflex stops. The results showed that angle measurements were consistent across the speakers, with lower and higher angle values corresponding closely to the relatively more posterior or anterior retroflex constrictions. An additional application of the method to X-ray tracings of Hindi/Urdu, Tamil, and Telugu retroflex consonants from previous studies confirmed the general suitability of the proposed method and suggested directions for further testing and research.