Hearing the trill or whistle of a bird while going about daily life is well known to boost people’s mood. But a new study suggests the psychological benefits of hearing birdsong are being threatened by traffic noise.

Researchers found that even low levels of traffic noise negatively affected the benefits to wellbeing that could otherwise be derived from listening to natural sounds.

Bird song has previously been associated with psychological benefits, including stress reduction and positive mood changes, while noise from traffic has been linked to both stress and annoyance.