The MATCH corpus: a corpus of older and younger users’ interactions with spoken dialogue systems

We present the MATCH corpus, a unique data set of 447 dialogues in which 26 older and 24 younger adults interact with nine different spoken dialogue systems. The systems varied in the number of options presented and the confirmation strategy used. The corpus also contains information about the users’ cognitive abilities and detailed usability assessments of each dialogue system. The corpus, which was collected using a Wizard-of-Oz methodology, has been fully transcribed and annotated with dialogue acts and “Information State Update” (ISU) representations of dialogue context. Dialogue act and ISU annotations were performed semi-automatically. In addition to describing the corpus collection and annotation, we present a quantitative analysis of the interaction behaviour of older and younger users and discuss further applications of the corpus. We expect that the corpus will provide a key resource for modelling older people’s interaction with spoken dialogue systems.     

Large Vocabulary Search Space Reduction Employing Directed Acyclic Word Graphs and Phonological Rules

Some applications of speech recognition, such as automatic directory information services, require very large vocabularies. In this paper, we focus on the task of recognizing surnames in an Interactive telephone-based Directory Assistance Services (IDAS) system, which supersedes other large vocabulary applications in terms of complexity and vocabulary size. We present a method for building compact networks in order to reduce the search space in very large vocabularies using Directed Acyclic Word Graphs (DAWGs). Furthermore, trees, graphs and full-forms (whole words with no merging of nodes) are compared in a straightforward way under the same conditions, using the same decoder and the same vocabularies. Experimental results showed that, as we move from full-form lexicons to trees and then to graphs, the size of the recognition network is reduced, as is the recognition time. However, recognition accuracy is retained since the same phoneme combinations are involved. Subsequently, we refine the N-best hypotheses' list provided by the speech recognizer by applying context-dependent phonological rules. Thus, a small number N in the N-best hypotheses' list produces multiple solutions sufficient to retain high accuracy and at the same time achieve real-time response. Recognition tests with a vocabulary of 88,000 surnames that correspond to 123,313 distinct pronunciations proved the efficiency of the approach. For N = 3 (a value that ensures we have fast performance), before the application of rules the recognition accuracy was 70.27%. After applying phonological rules the recognition performance rose to 86.75%.     

Reducing working memory load in spoken dialogue systems

We evaluated two strategies for alleviating working memory load for users of voice interfaces: presenting fewer options per turn and providing confirmations. Forty-eight users booked appointments using nine different dialogue systems, which varied in the number of options presented and the confirmation strategy used. Participants also performed four cognitive tests and rated the usability of each dialogue system on a standardised questionnaire. When systems presented more options per turn and avoided explicit confirmation subdialogues, both older and younger users booked appointments more quickly without compromising task success. Users with lower information processing speed were less likely to remember all relevant aspects of the appointment. Working memory span did not affect appointment recall. Older users were slightly less satisfied with the dialogue systems than younger users. We conclude that the number of options is less important than an accurate assessment of the actual cognitive demands of the task at hand.     

Quality of life of end-stage renal disease patients and study on the implementation of nocturnal home hemodialysis in Greece

The aim of this study was to measure the overall health-related quality of life of patients receiving hemodialysis in Greece and to assess willingness, motivation, and concerns about participating in a nocturnal home hemodialysis program. This review measured successfully the quality of life of 146 end-stage renal disease (ESRD) patients undergoing hemodialysis in 10 hemodialysis centers all over Greece and studied the factors that affect their choice to adopt a specific treatment. Physical and mental health status and health-related quality of life, measured by the Kidney Disease Quality of Life Short Form accompanied by the demographic data gathered, provide information that can help to improve ESRD patient care in Greece. A comparison with the Greek general population identifies lower physical functioning scores for the ESRD patients, while the mental functioning scores are comparable with those of the Greek general population. Moreover, it is important to notice the willingness expressed by half of the patients to participate in a potential program of nocturnal home hemodialysis.