Tonotopic sensitivity to supra-threshold hearing deficits of the envelope following response evoked by broadband stimuli

Scalp-recorded electrophysiological Envelope Following Responses (EFRs) have recently gained popularity as an objective measure of supra-threshold hearing deficits (e.g., as caused by cochlear synaptopathy). To explore the frequency specificity of EFRs in diagnosing deficits, we recorded EFRs to sinusoidally amplitude-modulated (AM) white noise carriers with different bandwidths in two participant groups: young normal-hearing control group and a group self-reported hearing difficulties in noisy listening environments. Despite individual variability in EFR strength, the group-means revealed minor response differences in stimuli with different low-frequency content. The limited contribution of auditory frequency channels below 2 kHz to the EFR was confirmed through EFR simulations from a biophysically-inspired model of the human auditory periphery. Further investigation showed that the minor low-frequency contribution stems from the lack of AM coding in individual low-frequency channels, although the overall spike-rate increases for stimulation with wider carrier bands. In conclusion, despite the broadband cochlear excitation, the broadband EFR mostly reflects summed AM coding strength in frequency channels above 2 kHz. To increase the frequency sensitivity of the EFRs it is necessary to carefully investigate the bandwidth and modulation frequency of the stimulus

Intelligibility of filtered speech and its relation to electrophysiological markers of supra-threshold hearing deficits

The origins and perceptual consequences of supra-threshold hearing deficits are not well understood. Sensory and neural deficits are likely contributors, underlining the need for an objective measure which quantifies the neural contributors and complements audiometric measures of sensory loss. The envelope-following response (EFR) is sensitive to neural fiber loss in animal models and has been proposed as a marker. However, its diagnostic sensitivity in humans and relationship to speech intelligibility are still unclear. Here we argue that the relationship between electrophysiological measures of temporal coding ability and the performance in speech-in-noise tasks crucially depends on the underlying stimulus parameters. We discuss ways in which experimental protocols can be adjusted to improve the predictive relationship between electrophysiological measures of temporal coding fidelity and behavioral measures of speech intelligibility and test these predictions in a group of young normal-hearing, elderly normal-hearing and elderly hearing-impaired participants as groups reflecting different degrees of neural or sensory hearing deficits

Enhancing the sensitivity of the envelope-following response for cochlear synaptopathy screening in humans : the role of stimulus envelope

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Understanding Pro-Environmental Behaviour as Process: Assessing the Importance of Program Structure and Advice-Giving in a Residential Home Energy Evaluation Program

Despite recognition that reductions in fossil-fuel usage are necessary to reduce environmental harm, energy consumption continues to rise globally. There is a growing need to understand how to effectively influence individuals to reduce their energy consumption, particularly of fossil-fuels. Pro-environmental behaviour is the subset of consumer behaviour that is oriented towards reducing environmental impact compared to other options. It is widely agreed that due to a multiplicity of influencers, pro-environmental behaviour is best analysed using an integrated approach that allows the inclusion of different disciplinary perspectives, and seeks to identify the most important influences in the system under study. This dissertation sought to address the broader challenge of how to better design programs and policies that result in behaviour that is more sustainable. The objective of this dissertation was to assess the importance and effects of program structure and advice-giving on the pro-environmental behaviour of participating in a home energy evaluation program that encouraged homeowners to implement energy efficiency retrofits. Program structure was defined as the combination of the price of the evaluation, the financial reward structure, the level of government support, and the focus on influencing eight specific decisions within a specified timeframe. Advice-giving occurred during the initial evaluation with a home energy advisor and with the delivery of the report that contained a set of recommendations. A convergent mixed methods research design was employed to assess the relative importance of the two factors on participation and advice-following, where advice-following was considered as the matching of decisions to recommendations. The quantitative dataset was made up of files that detailed the 13,429 initial and the 6,123 follow-up evaluations conducted by advisors of the Residential Energy Efficiency Project (REEP) in the Region of Waterloo between 1999 and 2011. The qualitative data were gathered through 12 interviews with home energy advisors, eight of whom had worked for REEP and had conducted more than half of the home energy evaluations contained in the quantitative dataset. A natural quasi-experimental intervention that measured self-selection in response to varying program structure was employed to examine for variations in participation, material characteristics of houses, recommendations, and advice-following. To extend our understanding of the process of participation and decision making patterns, other analyses focused on relationships between the number of recommendations, the time between initial and follow-up evaluations, the number and types of decisions made, and the prioritization of decisions. The interviews assessed for differences in styles of advice-giving, and for their impact through comparison with the quantitative data that detailed the recommendations and decisions taken by the homeowners. The results of the effects of both factors were interpreted jointly and compared to previous studies about REEP or the EnerGuide for Houses and program as it was delivered nationally. This dissertation confirmed that an integrated approach to examining pro-environmental behaviour is supported as a useful framework for analysis. The findings support a process-based definition of pro-environmental behaviour as a useful model and form of integration. A convergent mixed methods research design is supported as a valuable and rigorous approach to examine the impact of various influences simultaneously. The delineation of multiple stages in the decision making process greatly enhanced the quality of analyses and findings. The two main factors of program structure and advice-giving affected advice-following. One factor influenced the other, as the program structure affected the receptiveness of homeowners as perceived by advisors, which affected advice-giving. The findings support the importance of both behaviourist and social learning approaches in influencing pro-environmental behaviour, and that their importance varies depending on the stage of the decision process. The findings show that behaviourist interventions, such as the program structure, were associated with variations in participation, and that different subsets of the population of houses from the Region of Waterloo were attracted to the different program structures. Indeed, in each program structure, the decision to return was influenced by different decisions. A critical finding of this study was that these programs were not sufficient to alter the path dependence of energy consumption or of energy systems as the program participants usually did not implement the most effective retrofits, and if they did, the retrofits did not achieve adequate depth of reductions to energy consumption in a timely manner. According to the home energy advisors, many homeowners had pre-conceived ideas upon entering the program of replacing their heating systems and windows. The interpretation of the qualitative and quantitative data showed that these intentions were often not altered, particularly in the case of windows, the decision that advisors believed to be the least effective of energy decisions