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.

The Relationship between Materialistic Aspirations and Distinct Aspects of Psychological Well-being in a UK sample

The purpose of this research is to gain a deeper understanding of how materialistic aspirations are related to distinct aspects of psychological well-being. Research has consistently found a negative relationship between materialistic goals and well-being, but a review of the literature identified that the measures of well- being used in the majority of studies were measures of what Keyes (2002) describes as “subjective well-being” or “hedonic happiness”. Criticisms of these types of measures are that they fixate too much on the momentary experience of pleasure and don’t take into account what is meaningful and or what contributes to long lasting fulfilment. Very little research was found investigating the impact of materialism on “eudaimonic” well-being, which is found through doing what is worthwhile and realising ones potential and has been found to have a longer lasting impact on overall well-being (Huta & Ryan, 2010). To address this gap in the literature, a convenience sample of 113 adult subjects in the UK were recruited through Facebook and asked to respond to the Aspiration Index and the Psychological wellbeing scale. The relative importance placed on extrinsic (materialistic) and intrinsic aspirations was compared to the six dimensions of psychological well-being. In line with previous research, higher importance placed on materialistic aspirations for wealth, status and image were found to be negatively correlated with all aspects of psychological well-being. However, the strongest and only statistically significant negative correlation was between extrinsic aspirations and positive relations with others (r = -.256, p< 0.01). Positive relationships with other people form a central component of many theories of well- being and so this negative relationship may help to explain why materialistic aspirations are so consistently found to be negatively correlated to a variety of measures of well-being. Further research is needed to explore this relationship as no causation could be inferred.