While research on touch and smell in restoration remains limited, nature sounds and natural soundscapes are increasingly identified as important ecosystem services that can aid psychological restoration as well as well-being more broadly (Francis et al., 2017). Here soundscape is defined as the acoustic environment as perceived, understood, and/or experienced by people, in context (see International Organization for Standardization, 2014). However, the theories that seek to explain why certain environments facilitate restoration focus primarily on visual experience (see Ulrich, 1983; Kaplan and Kaplan, 1989). The first step in better integrating sound and soundscape into our theoretical understanding is to examine and review the available literature.
The sounds of nature are an integral part of environmental experience and appreciation (Mace et al., 2004) and quantitative studies also show that they play an important role in the way natural environments are perceived. For example, supplying nature sounds alongside visuospatial nature stimuli can significantly enhance positive appraisals of the setting, including preference and perceived restorativeness (e.g., Anderson et al., 1983; Jahncke et al., 2015; Franěk et al., 2018; Zhao et al., 2018; Zhu et al., 2020]. This may be due to an increased sense of presence in the environment generated by greater sensory input and awareness as a result of the presence of sound. Support for this argument comes from a body of qualitative work, described below, in which the experience of natural sounds is expressed as a desirable and immersive aspect of being in nature.
Assessments of these sounds as pleasant has implications for how beneficial they may be to listeners. Medvedev et al. (2015) integrated subjective ratings of environmental sounds and objective measures of stress recovery to show that ratings of natural sounds as pleasant were related to their ability to aid recovery from stress. In a questionnaire study of Swedish residents, Hedblom et al. (2017) found that women and older participants in particular reported finding nature sounds (such as birdsong and wind in leaves) calming, suggesting potential interactions between sound appraisal and demographics or individual differences.
Alvarsson et al. (2010) reported faster recovery in the nature condition than the low noise condition even though these were presented at the same sound pressure level (50dB LAeq, 4 min), suggesting that differences in the loudness vs. quietness of an acoustic environment may not be completely responsible for stress recovery. Instead, they suggest that the perceived pleasantness of the sounds may also be relevant and could pertain to their semantic content rather than merely their acoustic properties. In an extension of this work where sound pressure levels were controlled at an average of 64 dB SPL1 across conditions, Medvedev et al. (2015) observed faster decreases in skin conductance level following stress when participants were exposed to bird and water sounds, vs. sounds from the built environment.
Similar results are reported in studies of objective psychophysiological responses to natural sounds, even in the absence of a prior stress/fatigue condition. For example, Gould van Praag et al. (2017) found that participants who listened to familiar nature sounds showed better attentional monitoring and increased parasympathetic nervous activity than those who listened to artificial sounds. Jo et al. (2019) found that participants who experienced sounds of the forest displayed reduced signs of physiological arousal (i.e., reduced sympathetic nervous system activity) as compared to those who experienced urban sounds. Li and Kang (2019) found that listening to 5-min nature sound recordings (birdsong, ocean waves) led to reductions in certain signs of physiological arousal, including heart rate and respiration frequency and depth, whereas street and traffic soundscapes did not. Contrastingly, Hume and Ahtamad (2013) observed small but significant reductions in heart rate after listening to short (8-s) clips of unpleasant sounds.
Literature regarding effects of natural sounds on objective measures of cognitive performance, or cognitive restoration after fatigue, is also somewhat contradictory. On one hand, Emfield and Neider (2014) reported no significant differences in change in cognitive performance (as measured via pre- and post-exposure administration of a battery of cognitive tasks) as a result of listening to ocean and bird sounds, vs. urban sounds. Abbott et al. (2016) reported only marginally significant restorative effects of nature sounds on cognitive performance as measured via a backwards digit span task (BDST). On the other hand, Van Hedger et al. (2019a) reported significant improvements in cognitive performance (as measured by a composite dual n-back task and BDST) among participants exposed to nature sounds, as opposed to urban sounds, although surprisingly no such effects were found on change in affect. Among samples of school children, Shu and Ma (2019) found that listening to nature sounds (birdsong, water sounds) led to faster responses on a sustained attention to response task (SART) and increased performance on a digit span task (DST). In an in situ study in China where sound recordings were experimentally manipulated, Zhang et al. (2017) found that participants exposed to nature-based sounds showed greater attention restoration (as measured via performance on a mental arithmetic task) than those exposed to traffic or machinery sounds.
Imagine that after a tiring and stressful day, you find yourself in a peaceful and beautiful natural environment. All you hear there is the lovely bird's song, the rustling of the leaves and the sound of the stream. How do you feel?
The beneficial effects of nature sounds on human health have been known since ancient times. Ancient Greeks loved nature and this is evident in their mythology. Ancient greek myths and nature are inherently connected, proving that God, human beings and Mother Nature form an inseparable unity. Therefore nature is a source of life and this source has its own unique sound. But, how does this sound benefit human's health?
The basic elements of music are sound and rhythm, which are also found in nature. If you are wondering how this happens, it's simple. In nature the sounds are the animal's voice, such as the bird's song or the peaceful sound of lake water. On the other hand, everything in nature is a rhythm. The rain, for example, has its own rhythm. Rhythm is also hidden in the ocean waves or even in the sunrise and the sunset. Moreover, the rhythm of music is also reflected in the planet's movement and the cycle of the seasons. As a conclusion, it's understood that nature and music are one and nature influences music. Τhe majesty of nature has inspired many composers from different periods of classical music (including Handel, Haydn, Vivaldi, Beethoven, Schubert, Debussy etc). Especially during the period of Romanticism (1798-1837), the prevailing opinion was that nature is the mirror of soul. The fact is that in times of intense search for music, theorists and composers kept turning to nature and its sounds to find inspiration, new methods and ultimately new sounds. Many composers borrowed sound patterns from nature (insect and animal sounds, natural phenomena), which they transformed into musical forms.
Each environment includes a variety of sounds. People frequently don't fully perceive these sounds, because their attention is focused on the environment's view. Several researchers have studied the way people interpret the soundscape, as well as the effects of this interpretation on their behavior. The research results have shown that nature sounds can influence the psychological development of humans and represent the quality of their emotions. However, not all nature sounds affect the human mind the same way. This depends on the characteristics of each sound and how the listener receives it. From a biological point of view, sound is conceived by the human brain, played through his body, perceived by his sensory organs and then interpreted by his brain. Sounds, such as birds' song or the sound of running water convey a sense of security, relaxation and happiness. Furthermore, the sounds of nature affect the human brain in a special way, highlighting an experience. Thus, it is possible that a specific nature sound evokes a certain recall in the listener's mind.
The research and its results show that nature sounds help people to look at situations more holistically and put them in their real context. In this way, personal perspectives are broadened. Therefore, expanding man's relationship with nature and its sounds leads us to realize the unique benefits to human health and especially to mental health. Researchers have found that nature sounds work against anxiety and enhance nervous system function and human behavior. The calming effect of contact with nature and its unique sounds helps us reduce aggression and violence and contributes to the peace of mind. As a result, people's sociability is strengthened. In addition, focusing on the nature sounds helps to reduce stress, caused by the pressures of everyday life, making nature a source of mental peace. Moreover, researchers have shown in their studies that people's exposure to nature sounds improves their memory and contributes to a synchronized brain function. Last but not least, the connection with the sounds of nature improves concentration and efficiency. Consequently this connection is especially important for the healthy emotional development of human beings.
Undoubtedly, there is no better cure than nature itself. Nature is bursting with colors, life and sounds. These sounds are like a balm for the soul. Ancient Greeks believed that living close to nature offers harmony, balance and can lead to soul uplift. So, listen to the magical sound of nature and feel the happiness of life!