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Sounds in the garden: Designing acoustic design

In landscape design, every detail is important, so attention should be paid not only to how a garden looks, but also to how it sounds. A garden can not only reduce noise pollution in the city, it can also create its own soundscape that changes with the cycles of nature.

Author: Victor Matasov

There is a Zen parable. A new imperial garden was being prepared for opening for three years. Finally, all the work was completed, and the emperor invited all the nobility to admire the beauty of the garden. Everyone was delighted and complimented him. However, the Emperor was interested in the opinion of Master Lin-chi, who was considered to be a great connoisseur of the art of gardening. When the Emperor spoke to Lin-chi, everyone present turned around and there was silence. Lin-chi replied:

  • Strangely, I don’t see a single dry leaf. How can life exist without death? Because there are no dry leaves, the garden is dead. I think it was swept very thoroughly this morning. Order some dry leaves to be brought in.
    When the leaves were brought and scattered, the wind began to play with them. A rustle of leaves and the garden came alive!
    The master said:
  • Everything is all right now. Your garden is beautiful, but it was too tidy. Art becomes the greatest when it does not reveal itself.

Raymond Schaefer’s acoustic ecology

Apparently, Lin-Chee was versed in what we now call acoustic ecology. Its philosophical basis is simple: Raymond Murray Schafer – musician, composer and professor at Canada’s Simon Fraser University – suggested that we hear our acoustic environment as a musical composition and are responsible for it. Like many of the ideas that grew up in the late 1960s, Schaefer’s profound thought is now hidden behind the oft-used phrase, noise pollution.

Sounds in the garden: Designing acoustic design

Shafer’s first step was to point out the incredible predominance of visual information in society, the so-called “culture of the eye” (as this phenomenon has often been labelled in many works), and to point out that children’s listening skills were rapidly declining. Concerned about the problem, he began to argue fervently for the inclusion of “listening” in the curriculum. Schaefer suggested a set of exercises including “soundwalks” – walking routes with the main goal of becoming aware of the sound environment.

Acoustic ecological niches

We do, however, often forget about the sound around us, paying attention only to abrupt, out-of-place noises. Try to remember what sounds you hear in the garden? Birds singing, leaves rustling, a bee buzzing. You won’t be able to name them all at once. But listen carefully and you will notice that there are sounds that are specific to certain seasons, weather conditions and times of day. It’s all about the sound of the garden being subject to natural laws and rhythms.

Sounds in the garden: Designing acoustic design
The spike around 4 KHz is the call of a bird in its spectral niche. Source:
Barot, T. “Songbirds forget their tunes in cacophony of road noise”, The Sunday Times, January 10th 1999.

One major such pattern is described by the so-called spectral niche theory, according to which animal and insect vocalizations tend to occupy small frequency bands, leaving ‘spectral niches’ where other animal, insect and bird voices can build in. As urban spaces expand, the accompanying noise can block or mask the spectral niches, which in turn provokes species extinctions, according to Kraus’ research.

Research by the Royal Society for the Protection of Birds has confirmed that birds living near roads “cannot hear each other, leading to difficulties in song learning and communication for potential pair formation”.

Noise in St Petersburg and Moscow

Since the Industrial Revolution, a large number of unique soundscapes have been covered by a cloud of homogenised, anonymous noise produced by the urban landscape – ubiquitous traffic. In Russia, the sanitary standard allowable noise level during the day is 55 dBA (slightly louder than a downpour, but quieter than a quiet conversation), at night it is 45 dBA. Only 34.3% of St. Petersburg’s territory is within these limits. That is more than 2/3 of the population of the city on the Neva are in the zone of excessive noise. And in Moscow, according to experts, 3 to 6 million people live in areas of high acoustics. And their ears are exposed to noise flow equal to 90-100 dB (decibels) during the day, and up to 70 dB at night.

However, in this case, noise pollution is not just about the maximum permissible sound level. What matters is whether or not there are free spectral niches left.

Sounds in the garden: Designing acoustic design
Spectrogram of the sound environment. Source: Krause, B. L. Wild Soundscapes in the National Parks: An Educational Programme Guide to Listening and Recording, 2002.

Plants against noise pollution

Таким образом, при создании садового дизайна для начала предстоит разобраться с шумами. Эффективность шумозащитных полос зелёных насаждений обсуждалась, однако ею на практике часто пренебрегают, предпочитая строить шумозащитные стены из стекла и бетона, стоимость которых более высокая, но сроки сооружения более короткие. Но ведь мы говорим о саде, а не о магистральных автотрассах.

Thus, when creating a garden design, the first thing to do is to deal with noise. The effectiveness of noise barriers in green spaces has been discussed, but in practice they are often neglected, preferring to build glass and concrete noise walls, which are more expensive but quicker to build. But we’re talking about a garden, not a motorway.

For best results (1), soundproofing strips should be dense, dense from the ground to the top, perpendicular to the direction of the sound source, and the plants used should have large leaves. Trees can be classified according to their effectiveness in reducing noise in the city as follows (4):

  1. Noise reduction of 5-6 dB: hazel, American maple, warty birch, hawthorn, white alder, white dogwood, Canadian poplar.
  2. Noise reduction of 6-8 dB: rhododendron, forest beech, holly, currant, common lilac, common hornbeam, downy jasmine.
  3. Noise reduction of 8-10 dB: snowberry, Berlin poplar, sycamore lime.
  4. Noise reduction of 10-12 dB: white maple.

Designing green screens

Research conducted in Germany has found that conifers have a greater effect on high frequency sounds than deciduous trees. For medium frequency sounds, the most effective species are: birch, alder, linden, oak, rhododendron, beech, poplar, wild cherry, American pine and black pine. According to German and English studies, very dense coniferous plantings have the ability to dissipate maximum noise. Numerous studies carried out in Canada have identified several indicators that contribute to the effectiveness of green screens:

  • Noise reduction is proportional to the increase in tree crowns;
  • dependence of the noise protection efficiency on the location of the green screen in relation to the noise source (maximum efficiency is achieved if the screen is located at an angle of 900 to the noise source);
  • Significant increase in the effectiveness of the green screen when combining different sized species; and when combining deciduous and coniferous species;
  • an increase in the effectiveness of greenscreens when surrounded by lawns;
  • the topography of the area plays a very important role. A combination of green noise screens with embankments designed to achieve sound reflection is particularly effective.
Sounds in the garden: Designing acoustic design

Landscape and acoustic design

Now that the noise pollution has been dealt with, it’s time to fill the garden with pleasant sounds. First and foremost, the birds. Build bird feeders and birdhouses for them, plant tall shrubs, and the garden atmosphere will be filled with pleasant voices and beautiful singing. It is almost impossible to imagine garden sounds without insects: the chirping of grasshoppers and the buzzing of bees and bumblebees. They gravitate towards open glades with flowers and herbs – this is the main thing that can attract them to the garden. Bees not only detect the scent of flowers, but also the colour. Remarkably, in summer they prefer shades of red, while in spring they choose bright blue tones.

Both birds and insects are also attracted to open bodies of water. It is good if there is a place for a pond with a small stream on the plot. This will not only provide cool refreshment on hot days, but many hours of froggy concerts in the open air in the evenings.

Rain and wind… it seems they are just two sounds, but if you listen attentively what a wealth of tones can be distinguished. Each plant plays its own melody in a unique way. Big stiff leaves of walnut tree crackle in the wind, birch rustles quietly and pine tree even screeches sometimes. And when the rain hits those same leaves, they all have a special, “their own” sound.

Soundscape scenarios

If you’re just getting ready to plan your garden, start by assessing it from a new ‘listening point’. Acoustic ecology distinguishes between ‘acoustic environment’ and ‘soundscape’. The way in which humans perceive the acoustic environment is the soundscape, i.e. one is objective and the other is subjective. To describe the sound environment acoustic observations and measurements are needed, from which conclusions are drawn about noise pollution, blocked spectral niches, etc. Then several variants of the soundscape can be modelled for the projected site to get an idea of how the garden will ‘sound’ under different conditions. And then, once you have made your choice, you can begin to implement it.

  1. Schafer, R. M. The Tuning of the World, 1977, New York: Knopf, republished in 1994 as The Soundscape, Destiny Books, Rochester, Vermont.
  2. Krause, B. L. “The Niche Hypothesis: A hidden symphony of animal sounds, the origins of musical expression and the health of habitats,” The Explorers Journal, Winter 1993, pp. 156-160.
  3. Barot, T. “Songbirds forget their tunes in cacophony of road noise”, The Sunday Times, January 10th 1999.
  4. Москва-Париж. Природа и градостроительство. Под ред. Н.С.Краснощековой, В.И. Иванова. М.: “Инкомбук”, 1997.
Sounds in the garden: Designing acoustic design

Ph.D. in Geography, Associate Professor at the Department of Geography and Geoinformation Technologies of the Higher School of Economics; Associate Professor at the SUNlab Science Centre; Specialist in Landscape Ecology, GIS and Remote Sensing, Natural Heritage and Landscape Archaeology, Acoustic Ecology

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