Abstract In recent years research in the three‐dimensional sound generation field has been primarily focussed upon new applications of spatialized sound. In the computer graphics community the use of such techniques is most commonly found being applied to virtual, immersive environments. However, the field is more varied and diverse than this and other research tackles the problem in a more complete, and computationally expensive manner. Furthermore, the simulation of light and sound wave propagation is still unachievable at a physically accurate spatio‐temporal quality in real time. Although the Human Visual System (HVS) and the Human Auditory System (HAS) are exceptionally sophisticated, they also contain certain perceptional and attentional limitations. Researchers, in fields such as psychology, have been investigating these limitations for several years and have come up with findings which may be exploited in other fields. This paper provides a comprehensive overview of the major techniques for generating spatialized sound and, in addition, discusses perceptual and cross‐modal influences to consider. We also describe current limitations and provide an in‐depth look at the emerging topics in the field.

This Special Issue places in the foreground issues associated with the design and use of digital technologies and information systems in civil society. The idea for a Special Issue of Interacting with Computers emerged from two workshops held during 2003: ‘Can there be a social movement informatics?’, Leeds Metropolitan University in May and ‘Design for Civil Society’ at HCI 2003 (Dearden and Walker, 2003) in Bath. Together these workshops provided an initial opportunity for researchers and practitioners to come together to explore issues associated with civil society and social movement use of information and communications technologies (ICT). We now know that the ways in which technologies are designed, implemented and used are intimately related to context (e.g. Button and Harper, 1993; Orlikowski, 1992;,Kyng and Mathiassen, 1997; McCarthy et al., 1997; Brown and Duguid, 2000; Kling, 2000). Much research into information systems and technology is conducted in the contexts either of individual users, corporate organisations or, to a lesser extent, the state (or public) sector. This does not, though, exhaust the range of settings of ICT use. The term civil society has become widely used to refer to a ‘third’ sector of society, comprising those networks and institutions which operate independently of the state and outside commercial market relations. In this wide sense, civil society and social movements are crucial components of contemporary society (Castells, 1997; Anheier et al., 2001). It is also an arena in which ICT is frequently central. Arguably, ICT is one of the factors contributing to a growing significance of civil society. We might, then, expect characteristics that distinguish civil society from state and market to be reflected in the design and use of the technology in this sector.

The relationsh~p between the Robertson/Sptxck Jones relevancxi mighting formula and the Croft/Harper version for no relevanee information is d~ussed.A method of avoiding the negative weighta sometimes implied by the Cr&/Harper version is propowx$ which turna out to involve a return to the original Sparck Jones inverse collection frequency weight.The paper then goes on to propose a new way of using small amounts of relevanee information in the e9tim* tion of relevance weiglh Some experiments using TREC data are reported.1 A short hiiry This paper concerns the weighting of search terms as a searching mechanism, when there may be some relevance judgments on a f~documents in relation to the query or information need for which the search is being made.In this section, some elements of the history of relevance weighting are review@ as background to the present paper.Only those aspects relevant to the present discussion are covered.1.1 Inversecollectionfrequencyweighting Weighting terms accordiig to the number of documents in which they occur or to which they are assigned was d-vered empirically by Sparck Jones to be w ef%ctive search device [1].Frequent terms (that is, those that occur in many @cuments) are not in general good diecriminatm, and should be given low Weighs thus the weight should be inverdy related to the frequency.Such weighting is known as inverse document kquency (IDF) or inverse collection frequency.The usual formula is N w= logn where w is the weight to be assigned to the term, N is the size of (number of documents in) the collection and n is the number of documents in which the term occurs.Pmnkion to snakadigitalhrd mpicaofall of pad ofIhis materialfw pcraonal orClawoonlusc is_ withouifee providedthatthe copies arcnotmadaordkrimcd fw promor commercial advantage, the copy-n~tiistiti edtipbtiti dh-e, ddak givmthatcopyri

We discuss whether it is feasible to build intelligence rule- or weight-based algorithms into general-purpose software for interactive thesaurus navigation. We survey some approaches to the problem reported in the literature, particularly those involving the assignment of “link weights” in a thesaurus network, and point out some problems of both principle and practice. We then describe investigations which entailed logging the behavior of thesaurus users and testing the effect of thesaurus-based query enhancement in an IR system using term weighting, in an attempt to identify successful strategies to incorporate into automatic procedures. The results cause us to question many of the assumptions made by previous researchers in this area. © 1995 John Wiley & Sons, Inc.