The Need for a Speech Corpus

This paper outlines the ongoing construction of a speech corpus for use by applied linguists and advanced EFL/ESL students. The first section establishes the need for improvements in the teaching of listening skills and pronunciation practice for EFL/ESL students. It argues for the need to use authentic native-to-native speech in the teaching/learning process so as to promote social inclusion and contextualises this within the literature, based mainly on the work of Swan, Brown and McCarthy. The second part addresses features of native speech flow which cause difficulties for EFL/ESL students (Brown, Cauldwell) and establishes the need for improvements in the teaching of listening skills. Examples are given of reduced forms characteristic of relaxed native speech, and how these can be made accessible for study using the Technological University Dublin’s slow-down technology, which gives students more time to study native speech features, without tonal distortion. The final section introduces a novel Speech Corpus being developed at DIT. It shows the limits of traditional corpora and outlines the general requirements of a Speech Corpus. This tool–which will satisfy the needs of teachers, learners and researchers–will link digitally recorded, natural, native-to-native speech so that each transcript segment will be linked to its associated sound file. Users will be able to locate desired speech strings, play, compare and contrast them—and slow them down for more detailed study

DIT’s Dynamic Speech Corpus and Dialogic Fluency

Monologic fluency is characterised by a lack of pauses and a smooth oral delivery. Dialogic fluency in L1-L1 unscripted speech, however, is characterized by seeming dis-fluency, hesitations, false starts etc. Yet the L1 speakers make perfect sense to each other. The Dynamic Speech Corpus (DSC) currently being developed under the FLUENT project at the Technological University Dublin (DIT). In dialogue, language represents only one of the communication channels at play in what is a dynamic, unscripted social interchange rather than a stand-alone linguistic performance. The language stream is supplemented by pragmatic considerations and a greater emphasis on prosody. DIT’s DSC is based on natural, native-to-native dialogues and recorded at a high level of audio quality and is being developed mainly for autonomous learners. It will afford access to a unique audio resource based on unscripted dialogues between friends and acquaintances, exemplifying informal, native-speaker speech and natural turn-taking, rather than scripted interactions. The presentation demonstrates how users can locate and study samples of L1-to-L1 speech, as well as various phonetic phenomena such as speed-induced elisions in their full, pragmatic, dialogic context. This will allow the learner user to focus on the manner in which native speakers produce reduced forms and slow them down for detailed study. The corpus will be a rich resource for users who wish to study the communicative value of prosody and formulaic sequences, and particular attention will be paid to turn-taking strategies, along with other forms of interaction, which some researchers see as a ‘fifth skill’

HTML5 and the Learner of Spoken Languages

Traditional corpora are not renowned for being user friendly. If learners are to derive maximum benefit from speech corpora, then better interfaces are needed. This paper proposes such a role for HTML5. DIT’s dynamic speech corpus, FLUENT, contains a limited series of informal dialogues between friends and acquaintances. They are characterised by naturalness and their audio quality and marked-up using a schema which allows learners to retrieve features of spoken language, such as speaker intention, formulaicity and prosodic characteristics such as speed of delivery. The requirement to combine audio assets and synchronous text animation has in the past necessitated the use of browser ‘plug-in’ technologies, such as Adobe Flash. Plug-in-based systems all suffer from major drawbacks. They are not installed by default on deployed browsers. More critically they obscure the underlying speech corpus structure. Also proprietary UIs offer no standard way of dealing with accessibility or dynamic interface reconfiguration, e.g. moving from corpus playback to concordance views. This makes design of a unified interface framework, with audio playback, synchronous text and speech, more difficult. Given the profusion of plug-in architectures and plug-in types, it is clear that such an environment is unsustainable for building tools for speech corpus visualisation. In order to overcome these challenges, FLUENT drew heavily on the HTML5 specification coupled with a user-centred design for L2 learners to specify and develop scalable, reusable and accessible UIs for many devices.This paper describes the design of the corpus schema and its close integration with the UI model

Recent advances and validation of GIC modelling in the UK

We present a major upgrade to the power network model for the mainland UK and provide a validation of it with respect to both measured and synthetic data. Although we have only limited measured geomagnetically induced current (GIC) data with which to verify fully this updated model, we present an investigation of the sensitivity or accuracy of the model at each step in the modelling process: (1) The input geomagnetic field – we investigate the variability in modelled substation GIC with respect to network distance from magnetic field measurements made at magnetic observatories. (2) The electric field calculation - we use electric field measurements at the three UK observatories to test both the code and conductivity model used to compute the electric field across the UK. (3) The estimation of GICs in the power network - we use the test network provided by Horton et al. (2012), to test our modelling methodology and to validate the code at the GIC calculation step using a uniform electric field. (4) As a final step, we compare the output from the complete modelling chain with a small set of GIC measurements available for the March 2015 storm. We find that magnetic field measurements from observatories within a few hundred kilometres of the network can be used to estimate GIC within 30-40% of the true value; whilst observatories that are further away are less reliable, underestimating the largest values and recording false extremes. We also find good agreement between modelled and measured electric fields and GIC, giving us confidence that our models are providing sensible estimates of GIC. This research has benefitted from support from Natural Environment Research Council grant number NE/P017231/1

Validation of GIC in the GB High Voltage Network

The high-voltage (HV) power network of the mainland Great Britain (GB) consists of over 400 nodes and 750 connections. Using the National Grid Ten-Year Electricity Statement, we have developed an up-to-date model of the HV grid capturing the locations of the transformers, their connectivity and the overall topology of the network including double-circuits. We used the test network provided by Horton et al. (2012) to test our modelling methodology and to validate the code at the GIC calculation step using a uniform electric field. We then applied the same methodology to the GB grid and compared the output with a small set of GIC measurements available for the March 2015 and the September 2017 storm. We find reasonably good agreement between modelled and measured electric fields and GIC, giving us confidence that our models are providing sensible estimates of GIC at the sites where we have measurements. However, the GIC measurements are confined to a small region of the grid. As part of a wider programme, our next step will be to use the differential magnetometer method (DMM) to measure GIC under individual power lines across the UK over the next two years. We outline the approach that we will take to reconcile the flow of GIC within our model and the indirect measurements of GIC (as they will not be made at a transformer ground point). Ultimately, we wish to fully validate the HV grid model of GB (and as a complementary output the geoelectric field models) from the DMM measurements. This will allow future improvements such as transformer-level modelling and mitigation strategies to be tested

Dialogic Fluency - Why it Matters

Speech as an LSP: Many dialogues presented to language learners could be better described as ‘interleaved mini-monologues’, their purpose being to provide examples of grammatical sentences in realistic settings. Real dialogues, on the other hand, are worked out ‘live’, with neither speaker knowing in detail where the conversation will lead. Speaker interaction is marked to a large extent by prosody and often even good communicators sound disfluent if their half of the dialogue is judged in isolation. Dialogic fluency: The objective of dialoguing L1 speakers, however, is to realise a social or personal goal, with language only part of effective communication. Possibly the bulk of the communication devolves to prosody, shared knowledge and body language. Whereas this might not be a mainstream production goal for language learners, all users of English as an international language likely to come into contact with native speakers should be sensitised to native-speaker prosody. Influence of live dialogue on speech production: Given that the aim of an L1-L1 dialogue is not to provide learners with sample sentences, but rather to use language as a key factor in a social encounter, learners need a tool which will allow them to study the interaction of real dialogues. Of particular interest is the turn-taking behaviour of speakers, which is often flagged prosodically and produces utterances which, on the surface seem disfluent, but which on further analysis are seen to have an interactive function. The production of such a tool is the aim of the Dynamic Speech Corpus (DSC)

Geoelectric field measurement, modelling and validation during geomagnetic storms in the UK

Significant geoelectric fields are produced by the interaction of rapidly varying magnetic fields with the conductive Earth, particularly during intense geomagnetic activity. Though usually harmless, large or sustained geoelectric fields can damage grounded infrastructure such as high-voltage transformers and pipelines via Geomagnetically Induced Currents (GICs). A key aspect of understanding the effects of space weather on grounded infrastructure is through the spatial and temporal variation of the geoelectric field. Globally, there are few long-term monitoring sites of the geoelectric field, so in 2012 measurements of the horizontal surface field were started at Lerwick, Eskdalemuir and Hartland observatories in the UK. Between 2012 and 2020, the maximum value of the geoelectric field observed was around 1 V/km in Lerwick, 0.5 V/km in Eskdalemuir and 0.1 V/km in Hartland during the March 2015 storm. These long-term observations also allow comparisons with models of the geoelectric field to be made. We use the measurements to compute magnetotelluric impedance transfer functions at each observatory for periods from 20 to 30,000 seconds. These are then used to predict the geoelectric field at the observatory sites during selected storm times that match the recorded fields very well (correlation around 0.9). We also compute geoelectric field values from a thin-sheet model of Britain, accounting for the diverse geological and bathymetric island setting. We find the thin-sheet model captures the peak and phase of the band-passed geoelectric field reasonably well, with linear correlation of around 0.4 in general. From these two modelling approaches, we generate geoelectric field values for historic storms (March 1989 and October 2003) and find the estimates of past peak geoelectric fields of up to 1.75 V/km in Eskdalemuir. However, evidence from high voltage transformer GIC measurements during these storms suggests these estimates are likely to represent an underestimate of the true value

Modelling electrified railway signalling misoperations during extreme space weather events in the UK

Space weather has the potential to impact ground-based technologies on Earth, affecting many systems including railway signalling. This study uses a recently developed model to analyse the impact of geomagnetically induced currents on railway signalling systems in the United Kingdom during the March 1989 and October 2003 geomagnetic storms. The March 1989 storm is also scaled to estimate a 1-in-100 year and a 1-in-200 year extreme storm. Both the Glasgow to Edinburgh line, and the Preston to Lancaster section of the West Coast Main Line are modelled. No “right side” failures (when unoccupied sections appear occupied) are suggested to have occurred during either storm, and the total number of potential “wrong side” failures (when occupied sections appear clear) is low. However, the modelling indicates “right side” and “wrong side” failures are possible on both routes during the 1-in-100 year and 1-in-200 year extreme storms, with the Glasgow to Edinburgh line showing more total misoperations than the Preston to Lancaster section of the West Coast Main Line. A 1-in-100 year or 1-in-200 year extreme storm would result in misoperations over an extended period of time, with most occurring over a duration of 2–3 h either side of the peak of the storm

A detailed model of the Irish High Voltage Power Network for simulating GICs

Constructing a power network model for geomagnetically induced current (GIC) calculations requires information on the DC resistances of elements within a network. This information is often not known, and power network models are simplified as a result, with assumptions used for network element resistances. Ireland's relatively small, isolated network presents an opportunity to model a complete power network in detail, using as much real‐world information as possible. A complete model of the Irish 400, 275, 220, and 110 kV network was made for GIC calculations, with detailed information on the number, type, and DC resistances of transformers. The measured grounding resistances at a number of substations were also included in the model, which represents a considerable improvement on previous models of the Irish power network for GIC calculations. Sensitivity tests were performed to show how calculated GIC amplitudes are affected by different aspects of the model. These tests investigated: (1) How the orientation of a uniform electric field affects GICs. (2) The effect of including/omitting lower voltage elements of the power network. (3) How the substation grounding resistances assumptions affected GIC values. It was found that changing the grounding resistance value had a considerable effect on calculated GICs at some substations and no discernible effect at others. Finally, five recent geomagnetic storm events were simulated in the network. It was found that heavy rainfall prior to the 26–28 August 2015 geomagnetic storm event may have had a measurable impact on measured GIC amplitudes at a 400/220 kV transformer ground