Forests calm the heart, birdsong soothes the nervous system, study finds

Spending time in a forest slows the heart, and listening to birdsong helps the nervous system recover, even when the two experiences are delivered separately. That is the central finding of a new experimental study from North Carolina State University, published in Frontiers in Bird Science, which measured the physiological stress responses of college students exposed to different combinations of natural landscapes and natural soundscapes. The results suggest that the visual and auditory components of nature act through partially independent pathways, a discovery with immediate practical value for urban planners who rarely have the luxury of providing both trees and quiet at the same time.

The research team, led by undergraduate researcher Trent Ford, recruited 95 participants from North Carolina State University for a randomized, four-treatment, within-subjects experiment. Each participant experienced every combination of two landscapes and two soundscapes: a forest setting versus a gray, urban-like space, each paired with either recorded birdsong or recorded traffic noise. The design allowed the researchers to isolate the independent contributions of what participants saw and what they heard, rather than treating nature exposure as a single, undifferentiated experience.

Physiological stress was quantified with two well-established cardiovascular markers: heart rate and heart rate variability, the latter measured as the root mean square of successive differences between heartbeats, known as RMSSD. Heart rate is a straightforward index of cardiovascular arousal, while heart rate variability reflects the activity of the autonomic nervous system, with higher variability generally indicating greater parasympathetic engagement and a body in a state of recovery rather than vigilance. Each experimental session began with five minutes of silent control, followed by ten minutes of the assigned recorded soundscape, and every participant listened to each recording in both settings.

The statistical analysis relied on linear mixed models with a random intercept to account for repeated measures within each participant, and fixed effects for soundscape, landscape, their interaction, age, and gender. The results were clear on both fronts. Forest exposure was associated with a reduced heart rate relative to the gray space, with a coefficient of 0.65 and a p-value of 0.007. Birdsong exposure increased heart rate variability relative to traffic noise, with a coefficient of -1.38 and a p-value of 0.049. Crucially, the interaction between soundscape and landscape was not significant for either outcome, with all interaction p-values exceeding 0.16, meaning the two effects did not depend on each other.

That absence of an interaction is the scientific heart of the paper. The researchers had anticipated that physiological stress might only decrease among participants who simultaneously enjoyed a natural space and natural sounds, but the data told a different story. Time in a forested landscape and listening to birdsong each produced independent, positive effects on well-being. In the authors’ framing, visual and auditory nature cues appear to support physiological recovery through partially independent pathways: forest landscapes are associated with reduced cardiovascular arousal, while birdsong soundscapes are associated with increased autonomic recovery.

Lead author Trent Ford described the surprise directly. Across the four treatments, the team expected that physiological stress might only decrease for participants who were both in a natural space and listening to birdsong, he said, but instead they found that time in a forested landscape and listening to birdsong each had independent, positive effects on well-being. The finding complements a substantial body of previous research, much of it conducted in laboratory settings, showing that exposure to nature and birdsong improves mental and physiological health. This study extends that work outdoors, with real landscapes and wearable heart rate monitors, and focuses on a population, college students, that faces a well-documented mental health crisis potentially exacerbated by isolation from nature.

The practical implications reach well beyond campus greenspaces. Ford noted that providing access to forested landscapes where birdsong, rather than traffic noise, predominates would be the ideal scenario, but the research suggests urban planners have more options. When there is not room for trees, planners can design stress-reducing landscapes with traffic-calming measures that shift the soundscape balance away from traffic and toward birdsong. Conversely, when traffic noise is difficult to abate directly, additional tree cover may be beneficial by itself. In other words, the two levers of green infrastructure, visual and acoustic, can be pulled separately depending on the constraints of a given site.

For cities where land is scarce and noise is pervasive, this decoupling is more than an academic nuance. A pocket park beside a busy arterial road may still lower the heart rates of its visitors simply because it contains trees, even if traffic drones in the background. A treeless plaza on a quiet street may still aid autonomic recovery if its soundscape is dominated by birds rather than engines. Traffic-calming interventions, from speed humps to reduced speed limits, are already common tools of urban design, and this research gives them a new justification: they do not merely improve safety, they may actively reshape the acoustic environment in ways that measurably relax the human nervous system.

The study, titled Exposure to Forests and Birdsong May Reduce Physiological Stress Among College Students, was published on September 2, 2026, in Frontiers in Bird Science, with the DOI 10.3389/fbirs.2026.1884835. The co-author team includes Payton DeMay, J. Aaron Hipp, Lincoln R. Larson, Hannah M. Desrochers, Jackson Webb, Iris Howell, Made Ayu Pratiwi, Kushagra Meshram, JD Kluttz, Erin Foy, Griff Barlow, Caitlin McDade, Ivana Mali, Christopher E. Moorman and M. Nils Peterson of NC State University, along with Christian J. Bourke of the University of Georgia. The authors report no conflicts of interest, and the research was released as a peer-reviewed publication through North Carolina State University.

As with any single experiment, questions remain about how these effects generalize across ages, cultures, and environments beyond a university campus, and about how long-lasting the measured recovery might be. But the core message is unusually actionable. Nature’s benefits are not an all-or-nothing package requiring pristine wilderness. A canopy of trees and a chorus of birds each carry their own measurable physiological signature, and even modest, targeted interventions, a few more trees here, a quieter street there, can begin to deliver them. For a world in which most people live in cities and stress-related illness is rising, that is a finding worth listening to, ideally with birdsong in the background.

Subject of Research: Independent physiological stress-reduction effects of forest landscape exposure and birdsong soundscapes in college students

Article Title: Forest landscapes and birdsong soundscapes have independent physical health benefits

Article References: Forest landscapes and birdsong soundscapes have independent physical health benefits. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: birdsong, forest landscapes, physiological stress, heart rate variability, urban planning, green infrastructure, autonomic nervous system, college students, Frontiers in Bird Science, soundscape, nature exposure, North Carolina State University