Developing Amharic Spoken Dialogue System: A Hybrid Approach
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Date
2015-03
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Addis Ababa University
Abstract
This research attemps to propose an approache to make deciscions under uncertainity for
designing a dialogue manager for Amharic spoken dialogue system, Amharic as under-resourced
language. A prototype Amharic Spoken Dialogue System was implemented on hotel and
restaurant address information domain for experimentation. Data for this research was collected
through a method called Wizard of Oz and domain knowledge is prepared using address search
websites. How to design a dialogue manager which is robust for languages especially with low
performing Automatic Speech Recognition unit is a fundamental question of this research.
Previous studies on designing of spoken dialogue system for under resourced languages focused
mainly on Automatic Speech Recognizer. We reviewed methods and frameworks on dialogue
management. Design of Partially Observable Markov Decision Processes (POMDP) based
dialogue manager, which provides a principled framework to plan under uncertainity, yields
robustness. Low perfoming Spoken Dilaougue System (SDS) componenets, especially the
Automatic Speech Recognizer (ASR) were considered the causes of uncertainity. Maintaining
multiple hypotheses (evidences) improves the correctness of the dialogue manager. We
conducted experiments to test correctness score, error rate and robustness. With a maximum of 6
N-best list and 20 partitions the correctness score grow by 14.19%. Increasing the number of nbest
list of 6 reduced the error rate by 5.78% and with 6 n-best list. The belief updated below
0.12 seconds with 20 partitions and 6-nbest list. And the dialogue manager was able to complete
a task with an average 8.75 turns by 50% Word Error Rate. The finding from the research
illustrates that POMDP-based design approach to dialogue management is robust and possible to
develop an improving spoken dialogue system for under-resourced languages
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Keywords
Amharic as under-resourced language, A prototype Amharic Spoken Dialogue System