Why Listening Matters David Trevor Jones 1 Sustainable Acoustics Ltd., UK 47 The Street, Old Basing, Basingstoke, Hampshire RG24 7BX, UK Peter Rogers 2 Sustainable Acoustics Ltd., UK Unit 1, The Rural Business Hub Gander Down Barns, Rodfield Lane, Ovington SO24 0HS, UK

ABSTRACT Sound is the only one of our senses that remains active while we sleep. Through hearing we test our safety at distance and in the dark. It can also condition the way we feel. Noise can affect our health and well-being negatively but sound may do so positively. Acousticians are used to measuring noise but the more positive effects of sound less well understood.

The idea that sound can reduce stress and enhance our sense of wellbeing and even improve our health is a tantalising target for soundscape designs in the future but we need more fully to understand how to achieve it in a scientific way. We know that a tranquil place does not need to be quiet for instance, and that context and non-acoustic factors are important in the perception of tranquillity.

We know that natural sounds: waves breaking, rain, leaves rustling, water babbling, birdsong; and some anthropogenic sounds: a familiar voice, the murmur of conversation, music; can contribute to a positive soundscape.

Some examples and the current understanding of why this is, taking in cues from neuroscience, medicine and psychoacoustics are explored leading to quantification of these benefits for application in soundscape analysis and, ultimately, design.

1. INTRODUCTION

The content in a sound: the objective (e.g. anthropogenic) or subjective (e.g. natural) information in it, must influence the way that it is perceived. The evaluation of perception cannot be achieved by measurement, it necessarily requires listening. That is the proposition explored in this paper, with examples given to show why listening matters. 2. DISCUSSION Sound as perceived by the listener in context is at the heart of soundscape, where the sound quality is a function of the listener’s, or users’ perception and not just the objective physical characteristics [1]. It follows that as a consequence, its effect on the perceiver and their response to it must be a function of content, an emotional component that may exceed the purely

1 david@dtja.co.uk 2 progers@sustainableacoustics.co.uk

quantitative component in cause a response, whether it be by producing a stress hormone or releasing endorphins which relax the listener and provide a sense of release and restoration ?

Yet acousticians have for a very long time constrained themselves to the idea that sound and noise are effectively the same thing, which a simple numerical description is sufficient to describe in an objective way. This approach was largely supported by dose response relationships to different types of transportation noise and the development of the parameters and weightings commonly used. The acceptability of a sound environment, in planning terms, is still thought of largely as a function of the L Aeq [4], i.e. how loud it is when a filter that crudely simulated the human hearing ability at a certain level of sound is applied. But with a moment’s deeper thought it should be obvious that a single number is not and can not be sufficient to describe the perception of that sound. Perhaps we need to think of LOAEL 3 and SOAEL 4 , which come from noise policy in the UK [5] as having qualitative and contextual components as well as numerical ones, in order to expand the factors considered beyond simply numerical levels. An idyllic holiday location provides a simple demonstration of the challenge. Lucky enough to live, briefly, in a house on the beach the holidaymaker may throw open the bedroom window and sleep to the sound of the waves, fully connected to the natural sound in the environment. In contrast a dripping tap in the en-suite bathroom might drive them to distraction and prevent that sound sleep (i.e. good quality). The WHO night-time noise guidelines of 2009 [12] suggest that when quantified using traditional parameters the ‘noise’ of the sea would be a hazard to their health, while the noise from the tap is practically unmeasurable and so unlikely to cause disturbance, albeit it that such guidance is intended for anonymous sound. The information content and character of the sound are therefore critical to the holidaymaker’s perception and enjoyment of the experience and the numbers become irrelevant. The WHO guideline, indeed, is meaningless in this context.

A real example of the importance of listening to the sound rather than relying solely on a measurement of it comes from a baseline survey undertaken over a series of summer nights in semi-rural Hampshire, Southern England, UK. The survey position was on the edge of a village around 80 metres from a local main road. The average week-day sound level profile (8 days) is shown in Figure 1.

Figure 1 : DTJ752 Semi-rural Hampshire – Average day/night: Weekdays

3 Low Adverse Observable Effect Level 4 Significant Observable Adverse Effect Level

a Ta a :

The obvious feature of interest in figure 1 is the sudden uplift in all indices at about 04:30. This represents the start of the dawn chorus. The source was established by listening (not on the site itself but rather, at the consultant’s home in a comparable location about 40 km to the north). Subsequent measurements at home through the UK’s Covid-19 first lockdown in early Summer 2020 demonstrated that the dawn chorus started about 30 minutes or so before sunrise and follows that time as it moves through the Spring into Summer. During the period of the survey whose results are shown in Figure 1, the sun rose at about 04:50. The numerical analysis of the data produced an overnight average. of 46dB L Aeq,8hr with a standard deviation (SD) of 5dB. Dividing the night into pre-dawn chorus and chorus time yielded corresponding figures of 40dB/with 2dB SD and 51dB/with 2dB SD. The results were submitted to support a planning application for a small residential development and queried by the local Environmental Health Department.

The ‘night’ L Aeq,8hr propagated through an open window would exceed the Council’s bedroom amenity objective standard unless the windows could be kept closed with alternative ventilation. The proposed development, without that provision, would be in contravention of local policy. A debate ensued in which the consultant pointed out that if the dawn chorus was treated as ‘noise’ then all developments everywhere in that District would have to be treated as noise-affected (unless the supporting noise survey was conducted in Winter), whereas if it was treated as benign natural sound the site would easily meet the standard. Fortunately, common sense prevailed and the EH Department withdrew its objection and permission was granted. That outcome resulted directly and crucially from listening to the soundscape, and otherwise it may have resulted in a refusal.

Sleep disturbance risk features significantly in the planning process, as an indication of adverse effect level occurring with the potential for that being significant. It is generally accepted now that simple numerical sleep disturbance noise thresholds under real-life conditions are not as low as laboratory-based sleep studies in the 1980s suggested. A helpful synthesis in Appendix A to ProPG [4] reaches a cautious conclusion maintaining the WHO status quo, even having explored the evidence that it is a more complex issue. Stansfeld’s and Mattheson’s review some 14 years earlier [6] had explored the complexity of the relationship in more depth and offered more nuanced conclusions. The potential for sleep disturbance rests on a number of non-acoustical factors. Indeed, Fields had shown in 1993 [7] from reanalysis of a very large composite database that non-acoustic factors accounted for more of the annoyance response than sound level. Attitudinal factors feature in the disturbance and health effect relationships with noise level. An individual’s feelings about a noise and its source matter, and on a population scale there are identifiable differences between sources.

The human auditory system is a very highly complex and subtle thing. Objective research evidence is emerging for a differentiation, for example, between voices. A familiar voice does not trigger the same response that the voice of a stranger does. The distinction between the dawn chorus and road traffic noise in the early morning may be functionally and objectively no different but the human hearing system can tell the difference. A sensory system that can tell the temperature of water by its sound [4] can surely differentiate between the sound of road traffic and a waterfall, even if a frequency analysis suggests that they are not very different. It is encouraging that these attitudinal and qualitative subtleties are being recognised in the growing field of soundscape design.

Yang and Kang [9] advise “forget about the physics, think about what kind of sound” in the summary of their paper comparing subjective evaluation of sound level with acoustic comfort, peoples’ appraisal of level correlates with L eq but of comfort is correlated more strongly with source type. So the evaluation of sound effects on people is primarily a subjective issue rather than merely based on objective parameters. “reducing sound level does not necessarily lead to better acoustic comfort”. Kang has urged that our model for creating healthy, harmonious places to live should move from noise reduction to soundscape creation. This approach is adopted

clearly by the latest Frontiers Report by the UN in 2022, which identifies noise pollution as one of the emerging issues of concern, alongside Wildfires and Phenology (the changing rhythm of nature to climate change) [11]. It calls for “our cities to be aurally diverse and inclusive.. something silence alone can not deliver” and identified two shortcomings being any urban development strategy that environmental sound should be considered at the earliest possible stage of planning and design. The second is a shift from managing sound when it becomes pollution to being “opportunities for promoting healthy living environments”.

Whilst this is an important endorsement for a soundscape approach that relies on listening there are, no agreed tools and indices for measuring what constitute a positive soundscape, or one that is high quality. Whilst a methodology and framework do exists within the ISO [1,2,3]. Further guidance is needed however. No sound level meter or algorithm can take all of the myriad of subtle factors into account in determining whether the sound environment at a location is ‘good’ or ‘bad’. As pressure for ever more residential development generates conflicts between noise and amenity, and pushes settlement boundaries ever further out into the countryside, those tools are ever more urgently needed. The one tool that we do have at our disposal that can differentiate the complex and subtle factors in a soundscape and guide us in its perception is our own auditory system. The highly respected sound artist and composer, Pauline Oliveros, originated the discipline of ‘deep listening’. This, she urged, began with understanding the distinction between hearing and listening: “To hear is the physical means that enables perception. To listen is to give attention to what is perceived, both acoustically and psychologically” [10]. As acousticians engaged in resolving conflicts over annoyance, in planning land use to avoid yet more conflict and to produce healthy, harmonious and positive residential soundscapes and in urban soundscape design we must be conscious of what our ears – or more accurately, our auditory system – can tell us. Whether the dawn chorus is ‘noise’ or ‘sound’ starts with listening to it rather than just measuring it and the result can materially influence a planning decision and implicitly, those for a whole district. That is why listening matters. 3. CONCLUSIONS It is clear that it is not enough to rely on the objective ways that acousticians have done in the past where soundscape quality needs to be understood, as this is a poor indicator of perception.

Critical listening is therefore an important tool for an acoustician to use when dealing with assessments at the earliest possible stage of planning to be able to determine the parts of sound that affect how we feel in response, in the context it is being heard. Listening therefore does very much matter as instruments are not yet at a practical point where this can be done entirely objectively in a practical sense, although standards are emerging and guidance is needed. 4. REFERENCES 1. ISO/TS 12913-1:2014 Acoustics - Soundscape Part 1: Definition and conceptual

framework 2. ISO/TS 12913-2:2018 Acoustics - Soundscape Part 2: Data collection and reporting

requirements 3. ISO/TS 12913-3:2019 Acoustics - Soundscape Part 3: Data analysis 4. ProPG: Planning & Noise, UK. Professional Practice Guidance on Planning & Noise New

Residential Development. May 2017. Association of Noise Consultants / Institute of Acoustics / Chartered Institute of Environmental Health https://www.ioa.org.uk/publications/propg (accessed 31 July 2020)

5. Noise Policy Statement for England , Defra , (2010),

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_ data/file/69533/pb13750-noise-policy.pdf 6. Stansfeld, S.A. and Matheson, M.P. (2003) Noise pollution: non-auditory effects on health.

British Medical Bulletin 2003; 68: 243–257 DOI: 10.1093/bmb/ldg033 7. Fields, J.M. (1993) Effect of personal and situational variables on noise annoyance in

residential areas. The Journal of the Acoustical Society of America 93 , 2753 (1993); https://doi.org/10.1121/1.405851 8. Tanushree Agrawal , Michelle Lee, Amanda T. Calcetas, Danielle Clarke, Naomi Lin,

Adena Schachner Hearing water temperature: Characterizing the development of nuanced perception of auditory events(2020) . https://cognitivesciencesociety.org/cogsci20/papers/0089/0089.pdf 9. Yang, W. and Kang, J Applied Acoustics 66, (2), 211-229 (2005) 10. Pauline Oliveros The difference between hearing and listening (2003), TEDxIndianapolis

https://www.youtube.com/watch?v=_QHfOuRrJB8 (accessed 24 April 2022) 11. United Nations Frontiers Report (2022)

https://wedocs.unep.org/bitstream/handle/20.500.11822/38060/Frontiers_2022CH1.pdf 12. World Health Organisation, Night Noise Guidelines for Europe, ISBN 978 92 890 4173

7 (2009), https://www.euro.who.int/__data/assets/pdf_file/0017/43316/E92845.pdf