Hearing the Moment: Measures and Models of the Perceptual Centre

The perceptual centre (P-centre) is the hypothetical specific moment at which a brief event is perceived to occur. Several P-centre models are described in the literature and the first collective implementation and rigorous evaluation of these models using a common corpus is described in this thesis, thus addressing a significant open question: which model should one use? The results indicate that none of the models reliably handles all sound types. Possibly this is because the data for model development are too sparse, because inconsistent measurement methods have been used, or because the assumptions underlying the measurement methods are untested. To address this, measurement methods are reviewed and two of them, rhythm adjustment and tap asynchrony, are evaluated alongside a new method based on the phase correction response (PCR) in a synchronized tapping task. Rhythm adjustment and the PCR method yielded consistent P-centre estimates and showed no evidence of P-centre context dependence. Moreover, the PCR method appears most time efficient for generating accurate P-centre estimates. Additionally, the magnitude of the PCR is shown to vary systematically with the onset complexity of speech sounds, which presumably reflects the perceived clarity of a sound’s P-centre. The ideal outcome of any P-centre measurement technique is to detect the true moment of perceived event occurrence. To this end a novel P-centre measurement method, based on auditory evoked potentials, is explored as a possible objective alternative to the conventional approaches examined earlier. The results are encouraging and suggest that a neuroelectric correlate of the P-centre does exist, thus opening up a new avenue of P-centre research. Finally, an up to date and comprehensive review of the P-centre is included, integrating recent findings and reappraising previous research. The main open questions are identified, particularly those most relevant to P-centre modelling

Maximising spectral efficiency in LTE cells

The efficiency with which spectrum is used in wireless communications systems is becoming increasingly important as a result of the expected growth in traffic demand and the finite nature of usable spectrum. Spectral efficiency, defined as throughput divided by bandwidth, is a useful metric for evaluating the use of spectrum in wireless systems. In any given area the achievable spectrum efficiency is impacted by the underlying user population. This paper presents the methodology for finding the transmit power which maximises the spectral efficiency of a LTE cell for a given user density and traffic type. The impact of different user densities and traffic profiles on the choice of transmit power is evaluated. Results show that the transmit power which maximise spectral efficiency decreases as the user density and average data rate of the traffic profile increases. Two non ideal real world scenarios which require an increase in cell spectral efficiency are also considered and a modified user admission scheme which can increase the cell spectral efficiency is presented and evaluated. Results showed that the spectral efficiency was improved but the maximum improvement depended on the traffic profile and practical constraints of the LTE standard

Software defined radio architectures evaluation

This paper presents an performance evaluation of GNU Radio and OSSIE, two open source Software Defined Radio (SDR) architectures. The two architectures were compared by running implementations of a BPSK waveform utilising a software loopback channel on each. The upper bound full duplex throughput was found to be around 700kbps in both cases, though OSSIE was slightly faster than GNU Radio. CPU and memory loads did not differ significantly

A Novel Smart Device Student Response System For Supporting High Quality Active Learning In The Engineering And Science Disciplines

This paper proposes and presents a unique smart device student response system (SDSRS) that allows for a more flexible input than existing classroom response systems, such as clickers. This, in turn, allows students to respond to the lecturer with higher quality and more relevant information and, thus, improves their active learning. This is of particular relevance in the science and engineering disciplines where methodology is as important, if not more so, than the final answer. The SDSRS allows the lecturer to quickly obtain this pertinent information in real-time within the classroom environment. The proposed system consists of three main elements, namely a student sketch application, a lecturer view-and-edit application and a central cloud-based service to co-ordinate the exchange of information between the two applications. The system was evaluated within two different engineering classrooms, with very positive feedback obtained from both the lecturers and students involved. Details of the evaluation process, and the feedback obtained, are presented within

Automatic Blind Syllable Segmentation for Continuous Speech

In this paper a simple practical method for blind segmentation of continuous speech into its constituent syllables is presented. This technique which uses amplitude onset velocity and coarse spectral makeup to identify syllable boundaries is tested on a corpus of continuous speech and compared with an established segmentation algorithm. The results show substantial performance benefit using the proposed algorithm

A Novel Smart Device Student Response System For Supporting High Quality Active Learning In The Engineering And Science Disciplines

This paper proposes and presents a unique smart device student response system (SDSRS) that allows for a more flexible input than existing classroom response systems, such as clickers. This, in turn, allows students to respond to the lecturer with higher quality and more relevant information and, thus, improves their active learning. This is of particular relevance in the science and engineering disciplines where methodology is as important, if not more so, than the final answer. The SDSRS allows the lecturer to quickly obtain this pertinent information in real-time within the classroom environment. The proposed system consists of three main elements, namely a student sketch application, a lecturer view-and-edit application and a central cloud-based service to co-ordinate the exchange of information between the two applications. The system was evaluated within two different engineering classrooms, with very positive feedback obtained from both the lecturers and students involved. Details of the evaluation process, and the feedback obtained, are presented within

Practical Non-Uniform Channelization for Multistandard Base Stations

A Multistandard software-defined radio base station must perform non-uniform channelization of multiplexed frequency bands. Non-uniform channelization accounts for a significant portion of the digital signal processing workload in the base station receiver and can be difficult to realize in a physical implementation. In non-uniform channelization methods based on generalized DFT filter banks, large prototype filter orders are a significant issue for implementation. In this paper, a multistage filter design is applied to two different non-uniform generalized DFT-based channelizers in order to reduce their filter orders. To evaluate the approach, a TETRA and TEDS base station is used. Experimental results show that the new multistage design reduces both the number of coefficients and operations and leads to a more feasible design and practical physical implementation

Practical Non-Uniform Channelization for Multistandard Base Stations

A Multistandard software-defined radio base station must perform non-uniform channelization of multiplexed frequency bands. Non-uniform channelization accounts for a significant portion of the digital signal processing workload in the base station receiver and can be difficult to realize in a physical implementation. In non-uniform channelization methods based on generalized DFT filter banks, large prototype filter orders are a significant issue for implementation. In this paper, a multistage filter design is applied to two different non-uniform generalized DFT-based channelizers in order to reduce their filter orders. To evaluate the approach, a TETRA and TEDS base station is used. Experimental results show that the new multistage design reduces both the number of coefficients and operations and leads to a more feasible design and practical physical implementation

Locating Discontinuities in Synthetic Speech using a Perceptually Orientated Approach

A significant problem with unit selection based speech synthesis is the listener perception of sound discontinuities at which the speech waveforms are joined. This work demonstrates the application of three different perceptually motivated timefrequency representations and associated measures to the identification of such discontinuities

Efficient Channelization for PMR+4G and GSM Re-Farming Base Stations

Current trends in mobile communications look for a better usage of the frequency spectrum by diverging from the classic frequency bands division for each standard. Instead, sharing a same frequency band by several mobile standards has been motivated by several factors: under-utilisation of some frequency bands, better electromagnetic propagation properties and provision of new capabilities to existing standards. This new way to manage the electromagnetic spectrum has an influence in the devices which form the mobile radio interface: base stations and mobiles stations. In particular for base stations, channelization represents an important challenge. In this paper efficient channelization techniques are proposed as a practical solution for real world professional and commercial mobile communication cases where frequency bands are shared. Depending on each case, the most optimal solution is based on the application of one of these channelization techniques, or a combination of several of them