Phonological category quality in the mental lexicon of child and adult learners

• Aims and Objectives: The aim was to identify which criteria children used to decide on the category membership of native and non-native vowels, and to get insight into the organization of phonological representations in the bilingual mind. • Methodology: The study consisted of two cross-language mispronunciation detection tasks, in which L2 vowels were inserted in L1 words, and vice versa. In Experiment 1, 9-12-year-old Dutch-speaking children were presented with Dutch words which were either pronounced with the target Dutch vowel or with an English vowel inserted in the Dutch consonantal frame. Experiment 2 was a mirror of the first, with English words which were pronounced ‘correctly’ or which were ‘mispronounced’ with a Dutch vowel. • Data and Analysis: It was examined to what extent child and adult listeners accepted substitutions of Dutch vowels by English ones, and vice versa, and which vowel substitutions were accepted or rejected. • Findings: The results of Experiment 1 revealed that at that age children have well-established phonological vowel categories in their native language. However, Experiment 2 showed that in the non-native language, children tended to accept mispronounced items which involve sounds from their native language. At the same time, though, they did fully rely on their native phonemic inventory because the children accepted most of the correctly pronounced English items. • Originality: While many studies have examined native and non-native perception by infants, studies on first and second language perception of school-age children are rare. This study adds to the body of literature aimed at expanding our knowledge in this area. • Implications: The study has implications for models of the organization of the bilingual mind: while proficient adult non-native listeners generally have clearly separated sets of phonological representations for their two languages, for non-proficient child learners, the L1 phonology still exerts a big influence on the L2 phonology

Soiling and other optical losses in solar-tracking PV plants in Navarra

Field data of soiling energy losses on PV plants are scarce. Furthermore, since dirt type and accumulation vary with the location characteristics (climate, surroundings, etc.), the available data on optical losses are, necessarily, site dependent. This paper presents field measurements of dirt energy losses (dust) and irradiance incidence angle losses along 2005 on a solar-tracking PV plant located south of Navarre (Spain). The paper proposes a method to calculate these losses based on the difference between irradiance measured by calibrated cells on several trackers of the PV plant and irradiance calculated from measurements by two pyranometers (one of them incorporating a shadow ring) regularly cleaned. The equivalent optical energy losses of an installation incorporating fixed horizontal modules at the same location have been calculated as well. The effect of dirt on both types of installations will accordingly be compared

Speaker-normalized sound representations in the human auditory cortex

The acoustic dimensions that distinguish speech sounds (like the vowel differences in “boot” and “boat”) also differentiate speakers’ voices. Therefore, listeners must normalize across speakers without losing linguistic information. Past behavioral work suggests an important role for auditory contrast enhancement in normalization: preceding context affects listeners’ perception of subsequent speech sounds. Here, using intracranial electrocorticography in humans, we investigate whether and how such context effects arise in auditory cortex. Participants identified speech sounds that were preceded by phrases from two different speakers whose voices differed along the same acoustic dimension as target words (the lowest resonance of the vocal tract). In every participant, target vowels evoke a speaker-dependent neural response that is consistent with the listener’s perception, and which follows from a contrast enhancement model. Auditory cortex processing thus displays a critical feature of normalization, allowing listeners to extract meaningful content from the voices of diverse speakers

Speaking rate and spectral context affect the Dutch /a/ - /aa/ contrast

Dutch minimal word pairs such as 'gaas'-'gas' ("gauze"-"gas") differ in durational and spectral aspects of their vowels. These cues, however, are interpreted relative to the context in which they are heard. In a fast context, an "a" sounds relatively longer and is more likely to be interpreted as "aa". Similarly, when low frequencies in a context are perceived as dominant, high frequencies in the "a" become more salient, again more often leading to perception of "aa". A categorization experiment in which durational and spectral cues to the vowels were varied confirmed that Dutch listeners use both dimensions to distinguish between "a" and "aa". In Experiment 2, words were presented in rate- and spectrally manipulated sentences. Listeners, as predicted, interpreted the vowels relative to the context. An eye-tracking experiment will investigate the time course of these context effects and thus inform theories of the role of context in speech recognition

At which processing level does extrinsic speaker information influence vowel perception?

The interpretation of vowel sounds depends on perceived characteristics of the speaker (e.g., average first formant (F1) frequency). A vowel between /I/ and /E/ is more likely to be perceived as /I/ if a precursor sentence indicates that the speaker has a relatively high average F1. Behavioral and electrophysiological experiments investigating the locus of this extrinsic vowel normalization are reported. The normalization effect with a categorization task was first replicated. More vowels on an /I/-/E/ continuum followed by a /papu/ context were categorized as /I/ with a high-F1 context than with a low-F1 context. Two experiments then examined this context effect in a 4I-oddity discrimination task. Ambiguous vowels were more difficult to distinguish from the /I/-endpoint if the context /papu/ had a high F1 than if it had a low F1 (and vice versa for discrimination of ambiguous vowels from the /E/-endpoint). Furthermore, between-category discriminations were no easier than within-category discriminations. Together, these results suggest that the normalization mechanism operates largely at an auditory processing level. The MisMatch Negativity (an automatically evoked brain potential) arising from the same stimuli is being measured, to investigate whether extrinsic normalization takes place in the absence of an explicit decision task

A coupled optical-thermal-electrical model to predict the performance of hybrid PV/T-CCPC roof-top systems

A crossed compound parabolic concentrator (CCPC) is applied into a photovoltaic/thermal (PV/T) hybrid solar collector, i.e. concentrating PV/T (CPV/T) collector, to develop new hybrid roof-top CPV/T systems. However, to optimise the system configuration and operational parameters as well as to predict their performances, a coupled optical, thermal and electrical model is essential. We establish this model by integrating a number of submodels sourced from literature as well as from our recent work on incidence-dependent optical efficiency, six-parameter electrical model and scaling law for outdoor conditions. With the model, electrical performance and cell temperature are predicted on specific days for the roof-top systems installed in Glasgow, Penryn and Jaen. Results obtained by the proposed model reasonably agree with monitored data and it is also clarified that the systems operate under off-optimal operating condition. Long-term electric performance of the CPV/T systems is estimated as well. In addition, effects of transient terms in heat transfer and diffuse solar irradiance on electric energy are identified and discussed

An Ecology of Change – Teaching and Learning for Sustainable Development in the Tertiary Education Sector in the United Kingdom 2005-2014

In this thesis I advocate and evidence ESD through understanding and analysing the ecology of change in educational organisations, in particular Tertiary Education (TE), during the Decade of Education for Sustainable Development (UNDESD, 2005-2014). I draw on my portfolio of research that examined various aspects of the efforts to mainstream ESD during this decade. My publications, which are referred to in this thesis, are based on experience of my own practice as lecturer, educational development manager and advocate of ESD at local, national and global level. My research approach is broadly based on action research principles. I argue that, to fully understand this complex change process, it is necessary to appreciate the role of the underpinning, and often conflicting, values in TE and how they influence the adoption of ESD. I further discuss the influence of both ‘top-down’ approaches, that are expressed in policies and frameworks, and ‘bottom-up’ approaches that are instigated by communities and individuals with special interests. The influence of the learning environment itself is also examined. Lastly, I make the case that the employment of appropriate action research methodologies can help with gaining a better understanding of this process as well as play a part in the process itself

The uptake of spectral and temporal cues in vowel perception is rapidly influenced by context

Speech perception is dependent on auditory information within phonemes such as spectral or temporal cues. The perception of those cues, however, is affected by auditory information in surrounding context (e.g., a fast context sentence can make a target vowel sound subjectively longer). In a two-by-two design the current experiments investigated when these different factors influence vowel perception. Dutch listeners categorized minimal word pairs such as /tɑk/–/taːk/ (“branch”–“task”) embedded in a context sentence. Critically, the Dutch /ɑ/–/aː/ contrast is cued by spectral and temporal information. We varied the second formant (F2) frequencies and durations of the target vowels. Independently, we also varied the F2 and duration of all segments in the context sentence. The timecourse of cue uptake on the targets was measured in a printed-word eye-tracking paradigm. Results show that the uptake of spectral cues slightly precedes the uptake of temporal cues. Furthermore, acoustic manipulations of the context sentences influenced the uptake of cues in the target vowel immediately. That is, listeners did not need additional time to integrate spectral or temporal cues of a target sound with auditory information in the context. These findings argue for an early locus of contextual influences in speech perception