Gregory R. Watts

The state of tranquility: Subjective perception is shaped by contextual modulation of auditory connectivity

In this study, we investigated brain mechanisms for the generation of subjective experience from objective sensory inputs. Our experimental construct was subjective tranquility. Tranquility is a mental state more likely to occur in the presence of objective sensory inputs that arise from natural features in the environment. We used functional magnetic resonance imaging to examine the neural response to scenes that were visually distinct (beach images vs. freeway images) and experienced as tranquil (beach) or non-tranquil (freeway). Both sets of scenes had the same auditory component because waves breaking on a beach and vehicles moving on a freeway can produce similar auditory spectral and temporal characteristics, perceived as a constant roar. Compared with scenes experienced as non-tranquil, we found that subjectively tranquil scenes were associated with significantly greater effective connectivity between the auditory cortex and medial prefrontal cortex, a region implicated in the evaluation of mental states. Similarly enhanced connectivity was also observed between the auditory cortex and posterior cingulate gyrus, temporoparietal cortex and thalamus. These findings demonstrate that visual context can modulate connectivity of the auditory cortex with regions implicated in the generation of subjective states. Importantly, this effect arises under conditions of identical auditory input. Hence, the same sound may be associated with different percepts reflecting varying connectivity between the auditory cortex and other brain regions. This suggests that subjective experience is more closely linked to the connectivity state of the auditory cortex than to its basic sensory inputs.

Measurement and Subjective Assessment of Water Generated Sounds

There is increasing concern with protecting quiet and tranquil areas from intrusive noise. Noise reduction at source and barriers to transmission are mitigation measures often considered. An alternative is to attempt to mask or distract attention away from the noise source. The masking or distracting sound source should be pleasant so that it does not add to any irritation caused by the noise source alone. The laboratory measurements described in this paper consisted of capturing under controlled conditions the third octave band spectra of water falling onto water, gravel, bricks and small boulders and various combinations. These spectra were then matched with typical traffic noise spectra to assess the degree of masking that could be expected for each option. Recordings were also taken during each measurement and these were used later to enable the subjective assessment of the tranquillity of the sounds. It was found that there were differences between water sounds both in terms of masking and their subjective impact on tranquillity.

Tranquillity and soundscapes in urban green spaces—predicted and actual assessments from a questionnaire survey

A previous pilot study demonstrated the utility of a tranquillity prediction tool TRAPT for use in three green open spaces in a densely populated area. This allows the calculation of perceived levels of tranquillity in open spaces. The current study expands the range of sites to eight and, importantly, considers the views of visitors to these spaces. In total 252 face-to-face interviews were conducted in these spaces. An important aim of the survey was to determine the extent to which reported tranquillity obtained from the questionnaire survey could be predicted by a previously developed prediction tool TRAPT. A further aim was to determine what other factors may need to be considered in addition to the purely physical descriptors in TRAPT. The questions included the sounds and sights that were noticed, factors affecting tranquillity, as well as questions related to the benefits of visiting these areas. Predictions were considered satisfactory and could be improved further by taking account of issues surrounding personal safety. Examining the trends in these data, it was also shown that the percentage of people feeling more relaxed after visiting the spaces was closely related to overall assessments of perceived tranquillity. Further trends and their implications are presented and discussed.

Validation of a Tranquillity Rating Prediction Tool

Summary In both urban and rural environments, ‘tranquil space’ is predominantly constructed through the sensory information received by the auditory and visual modalities. This paper reports the results of a study that set out to validate and further develop a ‘Tranquillity Rating Predication Tool’, previously proposed by the authors [Pheasant et al. JASA 123(3), 1446‐1457 (2008)], which utilises the percentage of natural features contained within a scene and either of the noise indices LAmax or LAeq, as the key components. The results of the validation study show that when responding to combined audio-visual stimuli the A-weighted sound pressure level LAeq is most significantly related to the Tranquillity Rating. It is suggested that a modified measure of the visual composition of a scene incorporating contextual aspects is required. The findings of this work should be of particular interest to those charged with landscape management, such as the National Park Authorities, Regional Councils, and other agencies concerned with providing and maintaining public amenity.