Corpus-Based Information Presentation for a Spoken Public Transport Information System

The Alparon project aims to improve Vxos, Openbaar Vervoer Reisinformatie's (OVa) automated speech processing system for public transport information, by using a corpus-based approach. The shortcomings of the current system have been investigated, and a study is made of how dialogues in the OVR domain usually occur between a human operator and a client. While centering our attention on the presentation of information by the Automated Speech Processing (ASP) system, we describe the implications of this corpus-based approach on the implementation of our prototype. 1 I n t r o d u c t i o n The Alparon research group in Delft aims to improve Automated Speech Processing (ASP) systems for information retrieval and information storing dialogues. The current focus is on dialogue management for a research project of Openbaar Vervoer Reisinformatie (OVR) (Vark et al., 1996). OVR provides information about Dutch public transport systems, ranging from local bus services to long distance trains. They are developing an ASP system, called VIos, to automate part of its dialogues held at its call centres. Although the second version of VIos is implemented, it is far from perfect. After conducting user-appreciation studies it was clear that the next version of VIos should act more human like. This is the reason why we will take the human operator as the source of inspiration for improvement. The proposals that we will put foreward in this paper will be based on a study of about 100 human-human OVa-dialogues selected from a corpus of 5205 telephone conversations recorded at the This work is funded by OVP~ and Senter. call centers of OVa. The pilot corpus consists of dialogues that concern the exchange of train information only. OVR dialogues proceed in a specific way: first greetings are exchanged, then the client formulates his query, next the operator gives the desired information, and finally both parties say goodbye to each other. In this paper, we will concentrate on the improving the presentation of the travel scheme. We can roughly distinguish three different situations: the standard situation where everything runs smoothly, the situation where there is a repair operation by either the client or the operator, and the situation where a topic shift occurs. In our prototype, the dialogue manager and the text generator will collaborate to handle these situations. Since the dialogue manager has knowledge concerning known and new information, it can instruct the text generator to present the text in a natural way. In the next section, we will discuss related work. Then, we will describe in detail how information is presented in VIos and in the OVa corpus. Next, we will present the strategies an ASP system has to follow if such a system is to present information in a sensible manner. In the last section, we will describe future research. 2 R e l a t e d W o r k VIos is a Dutch version of the train timetable information system developed by Philips Aachen for the Deutsche Bundesbahn (Aust and Oerder, 1995; Aust et al., 1995). It was developed within the European LE-MLAP project MAIS (Strik et al., 1996), the aim of which was to make a Dutch and French version of the Philips system. A related European research project was the LEMLAP project RAILTEL (Bennacef et al., 1996) which strived to develop prototype telephone s e r vices for access to train travel information. Prototype systems are being developed for France