Rustling Leaves and Traffic Noise: Alpine Soundscapes

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What can you hear right now? Traffic noise outside the window? Colleagues chatting in the office? The wind in the trees, or perhaps the clatter of keyboards?

Most of the sounds surrounding us in modern life are human-made. In our bustling cities, the dense urban soundscape is gradually drowning out the subtler sounds of the natural world. What’s more concerning is that this is no longer just a “city problem.” Human-generated sounds are steadily creeping into even the most remote areas. Prof. Uta Schirpke and Manuel Ebner analyzed the soundscapes of more than 40 locations around Garmisch-Partenkirchen in Bavaria and found: even in seemingly pristine alpine locations, we are losing our acoustic connection to nature.

What are Soundscapes

A soundscape is the acoustic equivalent of a landscape. Just as a landscape encompasses everything you see, a soundscape includes everything you hear. Researchers categorize these sounds into four distinct groups:

• Geophony (earth-made sounds: wind, flowing water, rustling leaves)
• Biophony (wild animal-made sounds: birdsong, insect buzzes)
• Anthropophony (human-made sounds: voices, dog barking, cattle sounds)
• Technophony (technology-made sounds: cars, airplanes, industrial machinery)

How to research Soundscapes

The team installed 41 measuring points across various habitats, including moors, forests, alpine pastures and meadows, and rocky areas. The scale of the data was massive: After cleaning the files, the researchers were left with over 146,000 one-minute recordings. That is roughly 102 days of continuous audio. By sub-sampling and analyzing 820 specific files, they were able to pinpoint exactly which sounds dominated which environments.

What they found out

• Temporal patterns: Soundscapes follow the "diurnal cycle", the natural rhythm of sunrise and sunset. However, during daylight hours, the "Bio" and "Geo" sounds were often overshadowed by airplanes, traffic, and farm machinery. It was only under the cover of night that the wind and water regained their dominance.
• Spatial patterns: The composition of sounds we perceive is shaped by human infrastructure, topography, and land cover. Technophony, such as road traffic and machinery, tends to dominate valley bottoms and adjacent hillslopes, while aircraft noises are particularly present at high elevations. With increasing elevation and greater distance from human infrastructure, technological sounds diminish, while geophony increases with elevation and biophony with distance from roads. Overall, acoustic diversity is highest in valley bottoms, along hillslopes, and within forested areas.
• Technophony dominance: Technophony has become one of the most pervasive sound sources in mountain environments. Traffic and aircraft noise are audible almost everywhere, even in remote regions. This creates a masking effect, where continuous background noise makes it harder to perceive natural sounds.

Why this matters

Prolonged exposure to such noise can increase stress levels and negatively affect cognitive and physiological functioning. There is also a more subtle consequence: as we become accustomed to artificial noise, our ability to perceive and distinguish natural sounds, like birdsong, wind, or running water, diminishes.

Even animals are impacted by constant noise: Many species, like birds, rely on their voice for communication, navigation, and survival. Noise pollution can disrupt feeding behavior, reproduction, and overall ecosystem functioning.

What we can do

Addressing noise pollution requires action at multiple scales. At the policy level, measures such as transportation regulations, vehicle restrictions, and the designation of quiet zones can significantly reduce noise exposure. Locally, physical interventions like sound barriers or strategically placed vegetation can help buffer major noise sources.

On an individual level, we can start by listening more consciously. Can you hear birds? The rustle of leaves? Flowing water nearby? Paying attention to natural sounds in our daily lives can reduce stress – and perhaps help us reconnect with the environments we inhabit.

Read more on Uta Schirpke's research on sounscapes

This is what a soundscape analysis looks like: