Article

Synthesis of Studies on the Effects of Noise

1978-2024, with 2024 update

Project Summary

The Natural Sounds and Night Skies Division (NSNSD), within the Natural Resource Stewardship and Science Directorate (NRSS), develops, uses, and distributes the tools of natural and social science to help the National Park Service (NPS) fulfill its core mission: to protect park resources and values. As part of this, NSNSD strives to be aware of, understand, and communicate current scientific knowledge in our fields particularly as pertains to work that can help inform management of resources and the visitor experience. However, it can be challenging to stay abreast of scientific topics experiencing rapid growth in knowledge. This project addresses this challenge by conducting systematic, comprehensive, up-to-date queries and summaries of the scientific literature.

Noise arising from expansion of human population and infrastructure, transportation networks, and resource extraction alters conditions in public lands and protected areas, including national parks (Figure 1)1. In 2015, experts developed a comprehensive query to capture relevant literature on noise impacts to wildlife, which produced an authoritative literature synthesis2. That published synthesis offered an important peer-reviewed summary of the state of knowledge at the time. This project expands upon the 2015 effort by summarizing annual results from a systematic query of the literature. The intent is to provide park managers with an updated understanding of relevant scientific knowledge.

Notably, our approach is distinct from the results from an ad hoc query using Google Scholar or a related tool. We developed, tested, reviewed, and improved our query through an iterative process to ensure that the results encompass all the relevant literature. Though no tool can guarantee it will capture every relevant paper, our current process delivers results that are far more comprehensive than mere searches or less systematic queries.

This resource brief represents our continued attempt to concisely render knowledge of noise effects on wildlife and people in an accessible format. The project focuses on the size of the literature, the kinds of noise sources that were studied, and the breadth of effects that have been documented. We believe the value of this brief to NPS managers is to raise awareness of the extent of scientific support for park planning and management, and identification of distinct subsets of this literature that may be of special relevance for specific locations or management actions. The authors will assist parks and regions with more detailed and specific analyses of this literature upon request.

(clockwise from top left) Four photographs showing different noise sources heard in National Parks. a) helicopter and a herd of bison, b) bus and caribou crossing road, c) train next to a river, d) tour boat and bears on a nearby beach.
Figure 1. Within national parks, aircraft (a) and vehicle noise (b) are most frequently heard whereas train (c) and watercraft (d) are the loudest noise sources. Analysis is based on acoustic recordings collected and analyzed at 247 sites in 64 national parks across the United States3

Finding Relevant Studies

In 2018, we established a key term-based search of peer-reviewed literature published beginning in 1978, using Thompson’s ISI Web of Science (WOS). We tested the results against an established list of relevant papers on the effects of noise, capturing 90% of known studies using our search criteria.

Since then, we have conducted yearly literature searches following the same protocol, up to and including 2024. A subject matter expert reviews all papers identified by the search, to ensure that we include only studies documenting the ecological or health effects of noise in the final data set (N = 2329 relevant studies from 1978 to 2024). Irrelevant papers include those that summarize noise levels without documenting a response, and studies that occur inside hospitals and vehicles (indoor learning spaces are included, due to relevance for park interpretation). For papers deemed relevant, the subject matter expert labels each paper with a noise source category (e.g., transportation) and effect category (e.g., human, wildlife) (Figure 2). Additionally, we use automated searches to identify key words that appear in publication titles (e.g., sleep, annoyance, birds).

Number of Studies 1978-2024

A graph showing the increase in studies regarding effects of noise on humans and wildlife, annually 1978-2024. 1978: 9 human response studies. 1983: 12 human, 1 wildlife. 2014: 43 human, 37 wildlife. 2024: 67 human, 0 plant, 59 wildlife
Figure 2. The number of peer-reviewed studies published each year (1978-2024) documenting the effects of noise based on our WOS search criteria and manual verification. Note: this graphic excludes studies using laboratory animals.

Sources of Anthropogenic Noise 1978-2024

A subject matter expert labeled all relevant papers with a single category of noise source: noise from built environment (all sources together), recreation, transportation, resource extraction (which included industrial sources), or military (Figure 3). Most of the human studies are focused on transportation noise, while a large proportion of wildlife studies are focused on noise from the built environment. The “other” category reflects several studies on noise impacts from unmanned aerial vehicles (UAVs) (i.e., drones), with unspecified origin (i.e., military, recreation). There was 1 study on UAV noise impacts in 2020, and several more in 2021. 2021 and 2022 each produced a study on the impacts of anthropogenic noise on plants; previously, this literature had been sparse but may require attention in future years with growth in understanding of noise impacts to plants.

Pie charts. Human studies: 328 noise from generic/built sources, 4 military noise, 2 recreation noise, 151 resource extraction , 820 transportation. Wildlife: 437 noise from generic/built sources, 36 military, 8 recreation, 189 resource, 223 transport
Figure 3. Proportion of studies within different noise source categories. Human studies N = 1312; Wildlife studies N = 896. These graphics exclude studies using laboratory animals.

Keyword Trends from 1978 to 2024

From 1978-2024, there were 1312 studies on humans (101 of which were reviews), and 896 studies on wildlife (53 of which were reviews).

In the 1312 studies on human response to noise, article titles contained the following keywords:

  • 474 on traffic
  • 216 on aircraft noise
  • 299 on annoyance
  • 75 on wind farm noise
  • 164 on sleep
  • 50 on industrial noise
  • 39 on hypertension
  • 19 on speech
  • 9 studies in parks or protected areas
In the 896 studies on wildlife response to noise, article titles contained the following keywords:
  • 104 on traffic noise
  • 39 on underwater sonar
  • 19 on chronic noise
  • 12 on aircraft noise
  • 10 studies in parks or protected areas
Animated GIF with word clouds by decade. Key words: species, acoustic, exposure, sound, communication
The animated GIF shows word clouds of topic trends for wildlife publications from 1978-1989, 1990-1999, 2000-2009, 2010-2019, and 2020-2024. Early wildlife publications focused on dolphins and birds, while later studies included more diverse taxa (fish) and noise sources (e.g., urban, sonar, road).

Trends in topics 1978-2024

To examine different topics discussed in the literature, we generated word clouds for wildlife and human studies from the titles and abstracts for all publications (1978-2024).

Animated GIF of key words, by decade: traffic, exposure, annoyance, sleep, health, pollution
The animated GIF above is word clouds of topic trends for human publications from 1978-1989, 1990-1999, 2000-2009, 2010-2019, and 2020-2024. Early studies focused on annoyance from aircraft, and later studies included sleep and health effects of multiple noise sources (e.g., wind energy, traffic).
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2024 Update

The search for publications in 2024 produced 148 papers deemed relevant by a subject matter expert. There were 74 new studies on humans (7 of which were reviews), and 62 new studies on wildlife (3 of which were reviews). Additional studies were laboratory studies, which are not described in this summary.

In the 74 studies on human response to noise, article titles contained the following keywords:
  • 21 on traffic
  • 7 on aircraft noise
  • 7 on annoyance
  • 0 on wind farm noise
  • 5 on sleep
  • 2 on industrial noise
  • 2 on hypertension
  • 0 on speech
  • 0 studies in parks or protected areas
In the 62 studies on wildlife response to noise, article titles contained the following keywords:
  • 6 on traffic noise
  • 2 on underwater sonar
  • 1 on chronic noise
  • 2 on aircraft noise
  • 0 studies in parks or protected areas

Suggested Readings from 2024

In a study pertinent to recreation on public lands, Zeller et al. (2024) designed a field experiment in Bridger-Teton National Forest (Wyoming, USA) to quantify the impacts of recreation noise on several mammal species. The experiment found that recreation noise caused a higher likelihood of fleeing, increased vigilance, and reduced abundance the week after the noise treatment, with large vocal hiker groups and mountain bikers causing the highest probability of fleeing. Elk were the most sensitive species, while large carnivore species were the least sensitive.

Meanwhile, Meillere et al. (2024) found that noise directly impacts the growth and fitness of avian embryos. In an experimental study of zebra finch offspring, the authors showed that prenatal and postnatal exposure to traffic noise impaired nestling growth and caused telomere shortening across life stages until adulthood. This research indicates that traffic noise does not merely impact offspring fitness by disturbing parents – noise impacts offspring development directly.

Several studies in recent years have demonstrated the potential of ecological restoration using acoustic enrichment (e.g., using audio speakers to restore degraded coral reefs by guiding reef-building oyster larvae to restoration sites). Williams et al. (2024) combined aquarium and field experiments to further elucidate that marine noise pollution can mask acoustic enrichment and reduce the effectiveness of restoration efforts. Although noise pollution may compromise restoration efforts of acoustic enrichment, anthropogenic noise may also serve as an attractant for oyster larvae recruitment, and further research is needed.

Tennessen et al. (2024) examined the impacts of vessel noise on the foraging efficiency and success of two populations of fish-eating killer whales. They found negative impacts to all phases of foraging, from searching for, to pursuing, to capturing prey, with differences in efficiency and success by sex. As noise increased, both males and females were less likely to capture prey, but for different reasons. Males increased their searching effort and continued to pursue prey as noise levels increased (indicating that noise impaired male ability to capture prey), while females tended to forgo foraging under increasing noise.

Where to Find More Information

A searchable spreadsheet of all the relevant studies is available upon request (see contact information below). The spreadsheet is updated annually. In most cases, NSNSD staff has access to the full text of the publications and can share a link, email a pdf, or assist in finding the reference.

For a summary of past suggested reading, please click here [Word doc, 22 KB].

Project Contacts

Cathleen Balantic, PhD; Tyra Olstad, PhD. Natural Resource Stewardship and Science Directorate, Natural Sounds and Night Skies Division. Email: SoundscapeSupport@nps.gov

References

1Buxton et al. Noise pollution is pervasive in US protected areas. Science 356.6337 (2017): 531-533.

2Shannon et al. A synthesis of two decades of research documenting the effects ofnoise on wildlife. Biological Reviews 91(2016): 982-1005.

3Buxton et al. Anthropogenic noise in US national parks-sources and spatial extent. Frontiers in Ecology and the Environment 17.10 (2019): 559-564.

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Last updated: March 24, 2025