Tranquillity of external spaces / influence of acoustic and visual factors

Lead Research Organisation: University of Bradford
Department Name: Sch of Engineering Design and Technology


Despite still having around 27,000 public parks and gardens the number of tranquil spaces in the UK is becoming seriously compromised and has prompted systematic research into tranquillity mapping and the identification and protection of Quiet Areas. A systematic study into factors affecting tranquility is urgently needed in response to the European Directive on the Assessment and Management of Environmental Noise (END). Although defining quiet areas in accordance with the END using purely acoustical measures is an important step in protecting tranquil spaces, there is a need to go further and integrate both aural and visual factors into an overall descriptor that will be sufficiently precise and practical. There have been several attempts to study the cross-modal interaction and the link between the perceived degree of noise annoyance and specific visual settings. However, the relevant importance of visual and auditory stimuli for the construction of a tranquil space is far from being understood. The purpose of this work is to complete a detailed investigation on how the auditory and visual stimuli influence the perception of tranquillity in order to develop robust design tools for use in designing and protecting tranquil spaces in urban and rural locations. A unique feature of this project is the focused attempt to determine the bimodal estimate of tranquillity for a combined audiovisual scene. For this purpose a coherent team of optometry and acoustics experts has been assembled. The proposed work is a combination of field data collection and laboratory analysis. The work aims to achieve better understanding of the effects of visual and audio stimuli on the perception of tranquillity of rural and urban landscapes, refine a newly proposed engineering tool for the design of external tranquil spaces with a highly variable audio and visual characteristics and to provide multi-disciplinary training for MSc/PhD students, research and academic staff. For the first time a systematic work on the multisensory perception of tranquillity of external spaces affected by sounds will be examined using avanced method of integration of information. A representative range of locations will be identified at which audio and visual recordings will be taken based on a previously obtained database of landscape types. Special software will be developed to analyse objectively the termporal and spectral characteristics of the recordings. The recorded data will be also analysed using a representative number of subjects recruited for the new tests. Two unique psycho-acoustic suites available at the Universities of Bradford and Sheffield will be used for these experiments. The dependent variables will include an overall rating of tranquillity and the independent variables will include noise descriptors, sound quality indicators and visual parameters such as the space occupied by natural features in the scene and the number of people present. The results of the objective measurements and the subjective experiments will be merged with the existing tranquillity assessment database and analysed using appropriate software. A unique outdoor area (Peace Garden) on campus has been recently developed. This facility will be used to conduct experiments on tranquillity to test the developed design tool. The creation of the garden which is nearing completion was a result of a joint effort between various Schools at the Universities of Bradford and Sheffield who foresaw its use for a variety of research purposes including studies of tranquillity. The work will involve MSc/PhD students who study courses in Engineering, Life Sciences and Multimedia.
Description The key result is the development and validation of a new engineering tranquillity rating tool which is based on visual and audio characteristics of rural and urban landscapes. This tool links directly the objectively measured noise level, proportion of contextual features and a subjectively perceived tranquillity rating. An important deliverable is simple mathematical expressions suitable for practitioners who design and maintain restorative outdoor spaces with enhanced tranquillity.

An important part of this project was to consider the relative importance of uni- and bimodal stimuli (audio and visual) on the construct of the tranquillity space (Task 5). The simplest model here is one in which the combined audiovisual tranquillity estimate is equal to the mean of the unimodal estimates. Any departure from this simple model means that the effect of one particular modality is dominant. Our results show that the tranquillity rating fells into two distinct groups. For scenes with a combined high tranquillity rating, the combined rating is higher than the average of the unimodal estimates, i.e. the combined rating converges towards the higher of the unimodal estimates. For scenes with a low tranquillity rating the opposite is true, i.e. when a combined rating is lower than that expected from a simple mean of the individual ratings, the tranquillity rating converges towards the lower of the unimodal estimates. This result suggests that the visual quality of environment cannot be neglected in a soundscape quality evaluation exercise and contributes strongly to the tranquillity construct. We found that pupil size and heart rate measures do not represent physiological correlates of tranquillity ratings.

The collected stimuli were used in an additional fMRI study which was organised by Prof. Woodruff and Dr. Hunter of Cognition and Neuroimaging Laboratory at Sheffield. The results of this study demonstrate a significantly greater effective connectivity between the auditory cortex and medial prefrontal cortex in subjects presented with more tranquil scenes. This work is highly novel and it paves the way to the development of objective measures of the influence of environmental features on the mental states of individuals and populations.

The project results have been disseminated via conferences and journal publications 5 of which are listed in the Publication section. In total 9 journal and 8 conference publications have emerged from this project. 2 new grant proposals to the EPSRC are being developed as a result of this work. The team used part of the EPSRC funding to organise a final dissemination event which took place in Huxley Lecture Theatre at London Zoo on the 9th of October 2009. This event was opened by the Major of London, Mr Boris Johnson, and it attracted over 150 practioners from the UK.
Exploitation Route The tranquillity rating prediction tool developed as a result of this project is sufficiently practical to be used by consultants, environmental engineers and landscape architects to predict the visual and audio quality of external spaces. This work paves the wave to the development of a range of quantitative prediction models for assessing the restorative quality of internal and external spaces.
Sectors Communities and Social Services/Policy,Environment,Healthcare,Transport,Other

Description The tranquillity rating prediction tool which was developed as a result of this project has been used extensively by researchers to study the environmental noise quality in restorative urban environments such as parks, gardens and dedicated green spaces. This work has attracted interest of Defra, CAA, National Planning Policy Framework and National Trust.
First Year Of Impact 2010
Sector Communities and Social Services/Policy,Environment,Healthcare,Transport,Other
Impact Types Societal,Policy & public services

Description Attendance at Euronoise Conference in Edinburgh 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Peer review and feedback on the paper entitled "The role of audio-visual interaction on the perception of tranquillity"

High interest from academic and non-academic colleagues to the proposed Tranquillity Rating Prediction Tool
Year(s) Of Engagement Activity 2009
Description Attendance at Internoise Conference in Shanghai 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact A paper entitled "Managing tranquil spaces in urban environments" was presented

Peer review and feedback
Year(s) Of Engagement Activity 2008
Description Final Dissemination Event at London Zoo organised with Support from TfL 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact This final dissemination event was attended by 100+ consultants, policy makers, local authority representatives and researchers.

A much better understanding of the potential impact of this research and its relevance to the contemporary problems of noise pollution and its control.
Year(s) Of Engagement Activity 2009