Insights

Biophilic sound design.

First published in the Journal of Biophilic Design, Issue 16 – Sound.

Noise (i.e. unwanted sound) is known to have negative consequences on peoples’ health and wellbeing. As an example, it is estimated that at least 1.6 million healthy years of life are lost in western Europe alone due to road traffic noise. While reducing noise is a good thing, that does not mean that the goal is silence.

So what sounds are good? To some extent, it depends who you ask, and it certainly depends on the context. Nevertheless, natural sound sources (that you are used to) are overwhelmingly perceived as tranquil, regardless of upbringing/environment . Beyond the subjective improvements of feeling more comfortable, exposure to natural sound sources is shown to promote physiological expressions of relaxation, suppressing sympathetic nervous activity and reducing heart rate.

A study of skin conductance , a physical measure of stress, found that, post a stressor, after a sharp increase in skin conductance, participants would see their skin conductance steadily reduce. However, those exposed to audio of road traffic noise were observed to have their recovery plateau in comparison to those exposed to an audio recording of natural sound sources. This shows that sound can strongly influence how we recover from stress, and while limiting noise is good, promoting natural sounds too is better.

Therefore, wherever you are, whatever you’re doing, being in a restorative sound environment is in your interest. At work, it helps you have an effective break. At home, it can help you rest your mind. In a healthcare setting, it can promote recovery.

So how do we design a restorative sound environment? In practice we’re holistic beings, so sound environments cannot be designed in isolation. Soundscapes need to be contextually appropriate. Playing loud birdsong in an office (where there are obviously no birds), will not necessarily be perceived as relaxing by all and may even reduce cognitive performance. A more pragmatic approach is to design calm environments intuitively, without forgetting about sound. The keys are to not let noise ruin an environment; and to try to facilitate a diverse mix of natural positive sound sources where possible.

Greenery is good, for so many things, and perceptions of soundscapes is no exception to this – most of the time. Perceived biodiversity (which in an ideal world, would be due to actual biodiversity), generally promotes wellbeing and the presence of greenery in a residential setting is shown to be able to reduce the perceived annoyance caused by road traffic noise to a quantifiable extent . Moreover, research related to noise annoyance shows that factors such as having access to quiet areas, not being able to see a noise source, the presence of greenery and even how much someone trusts/accepts a development can influence relationships to a noise source. Therefore, generally promoting the things that we know make people happy goes hand in hand with how people interact with their sound environment.

Designing restorative sound environments is more straightforward outdoors than indoors, particularly as local sound sources indoors have such a strong influence on peoples’ perceptions of their environments. Soundscapes indoors are often dominated by human voices, which can be perceived differently by different people, in different contexts, and in different moods.

Therefore, indoors, providing a restorative sound environment is often about agency/choice and providing occupants with calm sound environment alternatives. By providing people with tranquil areas, we can facilitate restoration. Adding biophony indoors sensibly can be challenging. Therefore, considerations should be given to a person’s relationship to the outside. If a quiet environment can be provided, with access to green visuals outside, then this is a better outcome than a quiet environment alone. If rooms meant for rest can be located considerately, then it is possible to have scenarios where opening windows, should someone choose to, allows natural sounds in, rather than anthropogenic noise. These natural sounds can then be promoted. Otherwise, giving people access to tranquil external sound environments is the least we can do.