Adrianus J. van Hessen

The end of categorical perception as we know it

Comparing phoneme classification and discrimination (or categorical perception) of a stimulus continuum has for a long time been regarded as a useful method for investigating the storage and retrieval of phoneme categories in long-term memory. The closeness of the relationship between the two tasks, i.e. the degree of categorical perception, depends on a number of factors, some of which are unknown or random. One very important factor, however, seems to be the degree of bias (in the signal-detection sense of the term) in the discrimination task. When the task is such (as it is in 2IFC, for example) that the listener has to rely heavily on an internal, subjective, criterion, discrimination can seem to be almost perfectly categorical, if the stimuli are natural enough. Presenting the same stimuli in a much less biasing task, however, leads to discrimination results that are completely unrelated to phoneme classification. Even the otherwise ubiquitous peak at the phoneme boundary has disappeared. The traditional categorical-perception experiment measures the bias inherent in the discrimination task; if we want to know how speech sounds are categorized, we will have to look elsewhere.

Radio Oranje: searching the queen's speech(es)

The Radio Oranje demonstrator shows an attractive multimedia user experience in the cultural heritage domain based on a collection of mono-media audio documents. It supports online search and browsing of the collection using indexing techniques, specialized content visualizations and a related photo database.

Easy Listening: Spoken Document Retrieval in CHoral

Abstract Given the enormous backlog at audiovisual archives and the generally global level of item description, collection disclosure and item access are both at risk. At the same time, archival practice is seeking to evolve from the analogue to the digital world. CHoral investigates the role automatic annotation and search technology can play in improving disclosure and access of digitized spoken word collections during and after this transfer. The core business of the CHoral project is to design and build technology for spoken document retrieval for heritage collections. In this paper, we will argue that in addition to solving technological issues, closer attention is needed for the work-flow and daily practice at audiovisual archives on the one hand, and the state-of-the-art in technology on the other. Analysis of the interplay is needed to ensure that new developments are mutually beneficial and that continuing cooperation can indeed bring envisioned advancements.

Speech Recognition Issues for Dutch Spoken Document Retrieval

In this paper, ongoing work on the development of the speech recognition modules of MMIR environment for Dutch is described. The work on the generation of acoustic models and language models along with their current performance is presented. Some characteristics of the Dutch language and of the target video archives that require special treatment are discussed.