title: The Development of a Model of Audio Comfort in an Aviation Context
Creators: name: Aldridge, MA
Publisher: name: University of Liverpool Repository
Year: 2019

description: The Development of a Model of Audio Comfort in an Aviation Context – M.Aldridge The aim of this research was to develop a model of audio comfort. This model was developed to facilitate the comparison of different stimuli and their impact upon participants’ comfort. The thesis provides details of the human factors research undertaken as part of an Innovate UK funded project Improving the Propulsion Aerodynamics and Acoustics of Turboprop Aircraft (ImPAcTA) with Dowty Propellers. The thesis discusses the usage of the data obtained from this project in the development of a model of audio comfort. The thesis describes the initial stages in which the impact on cognitive performance and comfort are assessed in context of the physical properties of noise (Chapter 3). In this initial stage the results showed that there was a significant impact of both spectral content and decibel level on cognitive performance and reported discomfort. These results confirmed the efficacy of stimuli specific cognitive performance tasks in the measuring of discomfort when paired with a comfort questionnaire. With the usefulness of cognitive performance tasks being supported by the research carried out in Chapter the context in which noise was experienced was then examined (Chapter 4). To manipulate the context in which the noise was perceived the experiment varied the fidelity of a flight simulator. The results from this study showed that the reported immersion and presence participants experienced was related to both the comfort reported and task performance. The results demonstrated the need to consider the physical stimulus properties as well as environmental context and presentation methodologies in the assessment of comfort. The results also showed a significant impact of simulation fidelity on the assessment of comfort for an audio stimulus with consistent physical properties. The proposed model in this thesis is based on Rolls (1990) model of emotion. This model posits that there are parallels between comfort and emotion as defined by Rolls. In this model these parallels are based on the concepts of; elicitation of autonomic and endocrine responses, requirements to learn new and flexible behavioural responses to avoid/attain discomfort/comfort, motivation to take action, and facilitating communication. In the proposed model, comfort is represented as the centre of an x,y axis, movement on these axis are caused by the introduction or removal of primary or secondary reinforcers. Primary reinforcers refer to the experience of the discomfort stimuli while secondary reinforcers refers to the expectations a participant has of the stimuli and surrounding context. The impact of these reinforcers can be measured by cognitive task performance for primary reinforcers and perceived annoyance for secondary reinforcers. This model provides a novel method of predicting comfort that can be objectively measured and tested. The models assumptions were tested with use of both data collected previously (Chapter 4) and data from a new large scale study. Through the use of this data the assumptions of the model were confirmed with the model providing useful predictions of comfort from the metrics (Speech Identification Task, comfort questionnaire and Tanker Tracking Task) used.