Evaluating Use of the Doppler Effect to Enhance Auditory Alerts

This is an Accepted Manuscript of an article published by Taylor & Francis in International Journal of Human–Computer Interaction on 10/02/2021, available online: https://doi.org/10.1080/10447318.2020.1870818Auditory alerts are an essential part of many multi-modal interaction scenarios, particularly in safety and mission critical settings, such as hospitals and transportation. A variety of strategies can be employed in the design of auditory alerts, often orienting manipulation of volume and pitch parameters. However, manipulations by applying a Doppler effect are under-investigated. A perceptual listening test is conducted (n = 100) using multiple alert sounds that are subjected to a variety of volume, pitch, and Doppler manipulations, with the unaltered sounds serving as a benchmark. Applying a mixed methods approach consisting of inferential statistics and thematic analysis, it is found that decreases in volume and a Doppler simulation of a sound moving away reduce importance and urgency, increase safety, are harder to detect, and are perceived as being more distant in perceptions of auditory alerts. Further, increases in volume and a Doppler simulation of a sound approaching are effective in communicating safety, whilst pitch manipulations were much less effective. Further work is required to provide wider, ecologically valid, verification of these findings, particularly as to how listener detection of Doppler and volume manipulations can be improved

Fusion bonding of reinforced thermoplastic

A laboratory technique developed to produce fusion joints under carefully controlled conditions is described The technique was used to manufacture single-lap specimens from the reinforced thermoplastic APC-2, and the influence of processing temperature and surface degreasing on joint strength is presented The influence of laminate type, testing rate, bondline thickness and overlap length on joint strength were investigated, and the results from these tests are presented In order to enable mathematical modelling of fusion joints to be carried out, the shear stress-strain curve of the reinforced thermoplastic matrix, PEEK, was measured using the thick adherend specimen This curve is presented along with an analysis of the thick adherend specimen failure surface using scanning electron microscopy The influence of matrix viscosity on control of bondline thickness is also discussed The mathematical model of Hart-Smith was used to predict joint strength His theoretical analysis for the prediction of adherend failure was modified to consider the strain distribution in the composite adherends rather than stress distribution, and the derivation of this is presented A bi-elastic model for the prediction of adhesive shear failure was developed, and a comparison is made with the results from Hart-Smith's elastic-plastic analysis From the theoretical analyses, failure curves are presented for the three dominant failure modes of single-lap joints These are plotted as failure load/width against overlap length, and a comparison is made with the experimental results for the influence of overlap length and bondline thickness on joint strength for several laminates The influence of adherend thickness on predicted joint strength is also considered Finally, the work conducted into the development of a practical technique for producing fusion joints in APC-2 is presented The technique uses a direct heating method to heat the bondline through the thickness of the composite, and, therefore, a discussion is conducted into the effect of processing on the adherend material as well as the influence of processing parameters on joint strength

How does Term-time Paid Work Affect Higher Education Students’ Studies, and What can be Done to Minimise any Negative Effects?

This study aims to investigate the effects of term-time paid work on undergraduate students’ studies and what can be done to minimise any negative effects. Two studies were conducted; the first to establish the extent of students taking on paid work during term time, the impact it had on their studies and how they would like to be academically supported. The second study addressed students’ preferred methods of support, specifically seeking to establish guidelines about optimal methods. Almost two thirds of students within the study work during term time, with an average work commitment of 16 hours. Over two thirds of working students felt that their studies had been negatively affected by their paid work, whilst just over half of the students reported that their physical health had been affected, with just under a half describing mental health issues associated with working whilst studying. Over half the students thought that pre-recorded lectures would be the most suitable method of academic support and that the optimum length should be 60 minutes. In addition, a number of other asynchronous methods were identified. The results suggest that it is possible to support students more during their studies, and that the solutions are relatively simple. There is no suggestion that the methods of support will lessen the negative effects of working while studying, but they can be used to provide what students think might assist them to balance paid work and studying during term time. This study might be of interest to those supporting other groups of students who may require support with their studies, such as those with health issues, disabilities or care responsibilities

Soundscape mapping: comparing listening experiences

The perceived auditory environment is an increasingly important part of people’s everyday interactive experiences. While sound design is an established discipline in media such as video games and cinema, this is not the case in Human-Computer Interaction (HCI). HCI designers are rarely trained in sound design, and may not make the most effective use of sound in the design of interactions. Even when sound is at the centre of a design it is rarely evaluated to compare the experiences of designers and listeners. This dissertation reports work conducted to develop a way of comparing sound designers’ intentions for a sound design with the experiences of listeners. Literature on methods of measuring, classifying and visualising sound was reviewed, as well as approaches to sound design in different forms of media and computing. A published method for representing auditory environments was selected for preliminary studies. The four studies addressed to the difficulties of describing auditory environments and how they might be visualised. Two surveys were conducted in order to identify attributes of sound that would be meaningful to 75 audio professionals and 40 listeners. A way of classifying and visualising sound events and their distribution in physical environments was developed and evaluated.The soundscape mapping tool (SMT) was trialled with sound designs from a range of fields within media and computing. The experiences of both the designer and listeners were captured for each of the designs using the SMT. This work demonstrated that the SMT was suitable for capturing the intentions of 10 sound designers and the experiences of 100 listeners. The trial also provided information about how the SMT could be developed further. The dissertation contributes evidence that auditory environments can be abstracted and visualised in a manner that allows designers to represent their designs, and listeners to record their experiences

Modification of cardiovascular and renal risk factors using antagonists of the endothelin system

Chronic kidney disease (CKD) is an important independent risk factor in the development of cardiovascular disease (CVD). Indeed, patients with CKD are far more likely to die from CVD than reach end stage renal disease. Conventional cardiovascular risk factors and co-morbidity contribute to this increased risk of CVD. However, emerging evidence suggests other novel factors including inflammation, oxidative stress, and a shift in the balance of the vasodilator nitric oxide and vasoconstrictor endothelin system, are also important contributors. Despite increasing evidence that the endothelin system plays an important role in the development of CKD and CVD, there has been little research examining possible therapeutic benefits of its modification in patients with CKD. The overall aims of the work presented within this thesis were to examine CVD risk in patients with renal impairment and then to see what impact chronic inhibition of the endothelin system would have on risk factors for CVD and CKD progression. In the first two studies I examined markers of arterial stiffness (AS) and endothelial function in a cohort of patients with immune-mediated renal disease. I was able to show in the acute setting that improvement in renal function following treatment for these conditions leads to significant improvements in AS. Interestingly, in patients who were in remission from their renal disease, only classical cardiovascular risk factors appear to be linked to AS. In the next study I was able to prove that sitaxsentan, a selective oral ETA antagonist, did not cause functional blockade of the ETB receptor in man. This was the first study of its kind to confirm that a “selective” endothelin antagonist truly is selective in vivo: a finding that will allow more accurate mechanistic investigation of the ET system. In the final studies, I showed that in subjects with stable non-diabetic proteinuric CKD, chronic selective ETA receptor antagonism reduces blood pressure and AS, and that these systemic benefits are associated with an increase in renal blood flow and reduction in proteinuria. The reduction in proteinuria is most likely haemodynamic and linked to a fall in GFR and filtration fraction, similar to what is seen with ACE inhibitors. Importantly, these benefits were seen in patients already taking maximally tolerated renin-angiotensin aldosterone system blockade, suggesting that chronic endothelin antagonism could be an important future therapy in the management of CKD. In summary, I have shown that renal impairment can directly affect markers of arterial function and by inference increase the risk of CVD. Chronic antagonism of the endothelin system with ETA receptor blockers would appear to improve many of these biomarkers, including reductions in BP, AS and proteinuria. There were no adverse effects reported in these studies, suggesting that selective ETA antagonism may be safe enough for clinical development in CKD patients. Further larger clinical trials are warranted

Subjective Evaluation of Music Compressed with the ACER Codec Compared to AAC, MP3, and Uncompressed PCM

Audio data compression has revolutionised the way in which the music industry and musicians sell and distribute their products. Our previous research presented a novel codec named ACER (Audio Compression Exploiting Repetition), which achieves data reduction by exploiting irrelevancy and redundancy in musical structure whilst generally maintaining acceptable levels of noise and distortion in objective evaluations. However, previous work did not evaluate ACER using subjective listening tests, leaving a gap to demonstrate its applicability under human audio perception tests. In this paper, we present a double-blind listening test that was conducted with a range of listeners (N=100). The aim was to determine the efficacy of the ACER codec, in terms of perceptible noise and spatial distortion artefacts, against de facto standards for audio data compression and an uncompressed reference. Results show that participants reported no perceived differences between the uncompressed, MP3, AAC, ACER high quality, and ACER medium quality compressed audio in terms of noise and distortions but that the ACER low quality format was perceived as being of lower quality. However, in terms of participants’ perceptions of the stereo field, all formats under test performed as well as each other, with no statistically significant differences. A qualitative, thematic analysis of listeners’ feedback revealed that the noise artefacts that produced the ACER technique are different from those of comparator codecs, reflecting its novel approach. Results show that the quality of contemporary audio compression systems has reached a stage where their performance is perceived to be as good as uncompressed audio. The ACER format is able to compete as an alternative, with results showing a preference for the ACER medium quality versions over WAV, MP3, and AAC. The ACER process itself is viable on its own or in conjunction with techniques such as MP3 and AAC

Sound Stories: A Context-Based Study of Everyday Listening to Augmented Soundscapes

With an increasing number of everyday operations and communications becoming both automated and autonomous, ambient intelligent soundscapes are transforming to accommodate additional sonic feedback, and with it, new frameworks of listening. While this type of research and design of audio augmented technology is not new, the impact pre-existing acoustic environments upon listeners’ sense-making activities is rarely considered holistically. Much of the study into the design of effective auditory displays focuses on perceptual acuity and correct source identification, often at the expense of understanding the context of meaning-making. This paper presents a study involving 70 participants who listened to unidentified audio recordings of two archetypal everyday urban sound environments naturally containing artificial signals as well as typical sounds. Using a ThinkAloud protocol we investigated listeners’ approaches to meaning-making in both semantic and temporal dimensions. Through a semantic content analysis, we articulate five aspects of sonic meaning-making: spatial, descriptive, experiential, associational and narrative. We further analyse the use of these perceptual elements on a temporal plane, in order to investigate how listeners construct a narrative of what they hear in real-time, naturally evolving as each subsequent sound event is interpreted. Results suggest that while listeners attend to sound events and spatial characteristics of a sound environment at the beginning of a new listening situation, as the soundscape unfolds they utilize associations and familiarity in order to place individual sounds into increasingly coherent narratives. Finally, we suggest that this approach could provide sound designers and human–computer interaction specialists with a model for investigating the context aspects of a soundscape more holistically, allowing them to evaluate the effect of any new designed sounds prior to introduction into real-world environments

Evaluating Use of the Doppler Effect to Enhance Auditory Alerts

Auditory alerts are an essential part of many multi-modal interaction scenarios, particularly in safety and mission critical settings, such as hospitals and transportation. A variety of strategies can be employed in the design of auditory alerts, often orienting manipulation of volume and pitch parameters. However, manipulations by applying a Doppler effect are under-investigated. A perceptual listening test is conducted (n = 100) using multiple alert sounds that are subjected to a variety of volume, pitch, and Doppler manipulations, with the unaltered sounds serving as a benchmark. Applying a mixed methods approach consisting of inferential statistics and thematic analysis, it is found that decreases in volume and a Doppler simulation of a sound moving away reduce importance and urgency, increase safety, are harder to detect, and are perceived as being more distant in perceptions of auditory alerts. Further, increases in volume and a Doppler simulation of a sound approaching are effective in communicating safety, whilst pitch manipulations were much less effective. Further work is required to provide wider, ecologically valid, verification of these findings, particularly as to how listener detection of Doppler and volume manipulations can be improved