Using the interaural time difference and cross-correlation to localise short-term complex noises

The mammalian binaural cue of interaural time difference (ITD) and cross-correlation have long been used to determine the point of origin of a sound source. The ITD can be defined as the different points in time at which a sound from a single location arrives at each individual ear [1]. From this time difference, the brain can calculate the angle of the sound source in relation to the head [2]. Cross-correlation compares the similarity of each channel of a binaural waveform producing the time lag or offset required for both channels to be in phase with one another. This offset corresponds to the maximum value produced by the cross-correlation function and can be used to determine the ITD and thus the azimuthal angle θ of the original sound source. However, in indoor environments, cross-correlation has been known to have problems with both sound reflections and reverberations. Additionally, cross-correlation has difficulties with localising short-term complex noises when they occur during a longer duration waveform, i.e. in the presence of background noise. The crosscorrelation algorithm processes the entire waveform and the short-term complex noise can be ignored. This paper presents a technique using thresholding which enables higher-localisation abilities for short-term complex sounds in the midst of background noise. To determine the success of this thresholding technique, twenty-five sounds were recorded in a dynamic and echoic environment. The twenty-five sounds consist of hand-claps, finger-clicks and speech. The proposed technique was compared to the regular cross-correlation function for the same waveforms, and an average of the azimuthal angles determined for each individual sample. The sound localisation ability for all twenty-five sound samples is as follows: average of the sampled angles using cross-correlation: 44%; cross-correlation technique with thresholding: 84%. From these results, it is clear that this proposed technique is very successful for the localisation of short-term complex sounds in the midst of background noise and in a dynamic and echoic indoor environment.

European Union Approaches to Human Rights Violations in Kosovo before and after Independence

This article examines European Union (EU) approaches to the question of human rights violations in Kosovo before and after its proclamation of independence, in February 2008. While the 1999 NATO-led humanitarian intervention in the region was often justified as necessary due to the continuous abuses of human rights, perpetrated by the Serbian forces against the ethic Kosovo Albanians, the post-interventionist period has witnessed a dramatic reversal of roles, with the rights of the remaining Serbian minority being regularly abused by the dominant Albanian population. However, in contrast to the former scenario, the Brussels administration has remained quite salient about the post-independence context – a grey zone of unviable political and social components, capable of generating new confrontations and human rights abuses within the borders of Kosovo. Aware of this dynamic and the existing EU official rhetoric, it is possible to conclude that the embedded human rights concerns in Kosovo are not likely to disappear, but even more importantly, their relevance has been significantly eroded.