Abstract:

We describe Open CALL-SLT, an easy-to-use infrastructure for building speech-enabled online CALL courses designed to help beginner/low intermediate language students improve their spoken language skills. A course consists of a set of lessons, where a lesson takes the form of a short interactive dialogue between the system and the student; typically these dialogues will be organized around a theme like “buying a train ticket” or “checking into a hotel” At each turn, the system prompts the student with a multimedia file and a piece of text in the L1. For example, in an English-for-German-speakers course, the multimedia file might show a ticket clerk saying “How may I help you?”, and the L1 text might say “Frag : 2 Tickets nach London”. The student gives a spoken response in the L2, e.g. here “I would like two tickets to London”, which is processed using a speech recognizer and either accepted or rejected. The student will normally be able to answer in several different ways; the relationship between prompts and possible responses is defined using a minimal formalism based on regular expressions and templates. A script, written in a simple XML-based language, determines the next step in the dialogue. The formalisms used to specify prompts, responses and scripts are described in (Rayner et al 2014). The infrastructure has been thoroughly tested in a series of evaluations with 12-14 year old Swiss German students of English, which have so far involved about 100 students and produced about 13000 logged interactions (Baur et al 2013, 2014).

Previous work has all been organized around courses written by members of the development team. In the present paper, we describe how we have opened up the CALL-SLT platform so that external users can design and run their own interactive courses. Online documentation, including a tutorial organized around a simple example course, explains the process. Users upload course material to their private directory using an FTP client and compile it remotely through a web interface; when the course compiles correctly, they can then deploy it live on a server and test it over a web connection. The only equipment required is a laptop running a broadband internet connection and a headset.

The “Open” version of the system is currently in alpha testing. We describe user reactions and two sample courses written by external users. One is designed to help French-speaking university-level students improve their command of academic English vocabulary; the other teaches English-speaking people resident in Geneva how to make simple calls to the local police to report nuisances.

References:
[1] Baur C., Rayner M., Tsourakis N. 2013. A Textbook-based Serious Game for Practising Spoken Language. 6th International Conference of Education, Research and Innovation, (ICERI), Seville, Spain.
[2] Baur C., Rayner M., Tsourakis N. 2014. Using a Serious Game to Collect a Child Learner Speech Corpus. Proceedings of LREC, Reykjavik, Iceland.
[3] Rayner M., Baur C., Tsourakis N. 2014. CALL-SLT Lite: A Minimal Framework for Building Interactive Speech-Enabled CALL Applications. Proceedings of the WOCCI Workshop, Singapore.

Keywords:

CALL, speech, web, rapid development.