Birdsong is often one of the most comforting sounds in nature. A few minutes of listening to calls from trees or hedges can make a park feel calmer and more restorative. But new research suggests that this effect can quickly fade when traffic becomes part of the background.

A study involving more than 1,500 participants found that even relatively low levels of road noise could reduce the psychological benefits people experienced while listening to natural soundscapes.

The findings add to growing evidence that urban noise does more than irritate: it can interfere with some of the positive effects people gain from spending time around nature.

Birdsong Still Had a Positive Effect

Participants listened to nine simulated sound environments combining bird calls with varying levels of traffic noise. Afterwards, they answered questions about how relaxed, restored or stressed they felt.

The researchers found that birdsong itself generally improved wellbeing regardless of its acoustic characteristics. This supports previous studies linking natural sounds with lower stress and better mood.

Dr Eleanor Ratcliffe, an environmental psychology researcher at the University of Surrey and co-author of the study, explained that bird sounds are often among the natural noises people find most pleasant and relaxing.

Traffic Changed the Experience

The positive effect became weaker when road noise was introduced. Researchers found that traffic reduced the psychological benefits normally associated with birdsong. Heart-rate measurements from a smaller group of participants supported this pattern. Those hearing soundscapes that included traffic showed lower heart-rate variability, a sign associated with a stronger physiological stress response.

The effect was particularly noticeable in soundscapes that were already acoustically complex. One possible explanation is overstimulation: when too many sounds compete for attention, even pleasant natural noises may become harder to process.

Recognising More Birds May Help

The study also found an interesting link between perceived biodiversity and wellbeing. Participants tended to report greater benefits when they believed they were hearing a wider variety of bird species. The effect was even stronger among people who said they knew more about birds.

This suggests that the way people interpret a natural environment may matter almost as much as the sound itself. A park filled with different calls may feel richer and more engaging, especially to someone who can recognise what they are hearing.

Age Made a Difference Too

Younger participants reported higher levels of wellbeing than older listeners. Researchers suggested that differences in hearing ability could partly explain this. Younger people may be able to experience a wider range of frequencies and subtle details in natural soundscapes, making the listening experience more vivid.

What This Means for Cities

The findings have practical implications for urban design. Creating more parks and green spaces is important, but simply adding trees and grass may not be enough if those places remain dominated by traffic noise. Researchers suggested measures such as lower speed limits and thicker ground-level vegetation around parks to help reduce unwanted sound.

For individuals, the message is simpler. Listening to birds can be an easy way to connect with nature, whether during a walk, from a garden or even through an open window.

The study shows that sound deserves more attention when cities are planned. A green space may look peaceful, but if constant traffic overwhelms its natural soundtrack, visitors may miss part of the restorative experience they came for.