Synthesis of Studies on the Effects of Noise

1978-2023, with 2023 update

Project Summary

The Natural Resource Stewardship and Science Directorate (NRSS) develops, utilizes, and distributes the tools of natural and social science to help the National Park Service (NPS) fulfill its core mission: the protection of park resources and values. For scientific topics experiencing rapid growth in knowledge, producing a balanced summary of this knowledge is challenging, especially because the most recent articles may contain crucial, relevant information for management of resources and visitor experience. This project addresses the challenge of realizing balanced coverage through a stringent application of systematic, comprehensive queries 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. A comprehensive query that captures the relevant literature on noise impacts to wildlife and park visitors was developed by experts who conducted original research in this area and published an authoritative synthesis of the literature². That published synthesis offered an important, peer-reviewed summary of the state of knowledge at the time of submission. However, its relevance diminishes with time when the literature expands and evolves rapidly. To offer relevant updates, this resource report represents a summary of the results from our systematic annual query of the literature, providing park managers with an accessible perspective of the size and scope of the relevant scientific knowledge regarding the effects of noise on wildlife and park visitors.We emphasize the distinction between our approach and the results from an ad hoc query using Google Scholar or a related tool. Our query was developed and tested - by experts in the field - to ensure that the results encompassed all the relevant literature. This query was reviewed and improved in an iterative process. Though no query can guarantee it will capture every relevant paper, our current query delivers results that are far more comprehensive than our initial searches, even though those initial searches were performed by experts in the field. In the context of offering a comprehensive, balanced assessment of the literature of noise effects on humans and wildlife, we are confident that our present query is the best tool to identify the pertinent papers.This resource brief represents our continued attempt to concisely render knowledge of noise effects on wildlife and people in an accessible format. The focus here is 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.

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 peer-reviewed literature search using Thompson’s ISI Web of Science (WOS). The search included papers published after 1977 to ensure all relevant literature was captured. The search was optimized to capture a known list of relevant studies. Ninety percent of the studies were captured using our search criteria. We feel that enlarging the query beyond its present scope is likely to add very few relevant papers, at the expense of adding many more irrelevant papers.Since then, we have conducted yearly literature searches following the same protocol, up to and including 2023. All papers were reviewed by a subject matter expert such that only studies focused on documenting the effects of anthropogenic noise were included in the final data set (N = 2167 relevant studies from 1978 to 2023). Papers that were not relevant included those that summarized noise levels without documenting a response, and studies that occurred inside hospitals and vehicles (indoor learning spaces were included, due to their relevance for park interpretation). For papers deemed relevant, the subject matter expert labeled each paper with a noise source category (e.g., transportation) and effect category (e.g., human, wildlife). Additionally, studies were automatically labeled using key words that appeared in the title of the publication (e.g., sleep, annoyance, birds).

Number of Studies 1978-2023

Figure 2. The number of peer-reviewed studies published each year (1978-2023) documenting the effects of noise based on our WOS search criteria and manual verification. Note: this graphic excludes studies using laboratory animals. For an alternative way to read this data, see the table at the bottom of this page.

Source of Anthropogenic Noise 1978-2023

All relevant papers were labeled by a subject matter expert with a single category of noise source: noise from built environment (all sources together), recreation, transportation, resource extraction (which included industrial sources), or military. 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.

Figure 3. Proportion of studies within different noise source categories. Human studies N = 1229; Wildlife studies N = 830. These graphics exclude studies using laboratory animals. Data for figure 3 is included in the alternative text below.

Keyword Trends from 1978 to 2023

From 1978-2023, there were 1229 studies on humans (93 of which were reviews), and 830 studies on wildlife (50 of which were reviews).In the 1229 studies on human response to noise, article titles contained the following keywords:

• 481 on traffic
• 216 on aircraft noise
• 296 on annoyance
• 78 on wind farm noise
• 163 on sleep
• 48 on industrial noise
• 38 on hypertension
• 19 on speech
• 10 studies in parks or protected areas

In the 830 studies on wildlife response to noise, article titles contained the following keywords:

• 105 on traffic noise
• 37 on underwater sonar
• 19 on chronic noise
• 10 on aircraft noise
• 10 studies in parks or protected areas

The animated GIF shows word clouds of topic trends for wildlife publications from 1978-1989, 1990-1999, 2000-2009, 2010-2019, and 2020-2023. 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 1978-2023

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 (1978-2023).

The animated GIF above is word clouds of topic trends for human publications from 1978-1989, 1990-1999, 2000-2009, 2010-2019, and 2020-2023. 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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2023 Update

The search for publications in 2023 produced 136 papers deemed relevant by a subject matter expert. There were 67 new studies on humans (6 of which were reviews), and 66 new studies on wildlife (7 of which were reviews). Additional studies were laboratory studies, which are not described in this summary.In the 67 studies on human response to noise, article titles contained the following keywords:

• 31 on traffic
• 8 on aircraft noise
• 4 on annoyance
• 3 on wind farm noise
• 8 on sleep
• 0 on industrial noise
• 1 on hypertension
• 0 on speech
• 1 studies in parks or protected areas

In the 66 studies on wildlife response to noise, article titles contained the following keywords:

• 8 on traffic noise
• 0 on underwater sonar
• 1 on chronic noise
• 0 on aircraft noise
• 0 studies in parks or protected areas

Figure 4. The number of peer-reviewed studies published each year (2000-2023) documenting the effects of noise based on our WOS search criteria and manual verification. Note: this graphic excludes studies using laboratory animals. For an alternative way to read this data, see the alternative text at the bottom of this page.

Suggested Reading

In a review of field studies examining the impacts of noise on wild fish, Pieniazek et al. (2023) comprehensively summarize different data collection methods (e.g., camera, diver, tissue analysis, hydrophone), impact sources (e.g., noise from boats, air guns, tones, pile drives), future research directions, and emerging approaches. This work offers a helpful entry point for exploring the current state of research on noise impacts to wild fish.Meanwhile, Kok et al. 2023 provide a review of how chronic noise can affect wildlife communities in both terrestrial and aquatic ecosystems. Although community-level impacts of chronic noise exposure are not yet well-understood, the available studies indicate that noise has direct and indirect impacts, and effective mitigation will be difficult to accomplish without addressing knowledge gaps. Knowledge gaps persist due to the challenges involved in conducting the comprehensive long-term studies necessary to address community-level questions. The authors provide suggestions and a road map to address current knowledge gaps.Finally, Kleist et al. 2023 studied sites in 40 U.S. national parks to investigate whether birds respond differently to noise sources that could be clearly associated with the physical presence of a source (vehicle noise, human voice), vs. “disembodied” noise sources that a bird might not be able to easily associate to the physical source (aircraft overflight). The researchers observed an increased probability of detecting birds immediately after noise events, with effects persisting several hours afterward. The effects were strongest for aircraft noise, which might be particularly problematic since animals cannot easily move to avoid far-reaching aircraft noise the way they may be able to avoid vehicle noise or human vocal noise.

• Kleist, N. J., Fristrup, K. M., Buxton, R. T., McKenna, M. F., Job, J. R., Angeloni, L. M., … & Wittemyer, G. (2023). Anthropogenic noise events perturb acoustic communication networks. Frontiers in Ecology and Evolution, 11, 1149097. Open Access.
• Kok, A., Berkhout, B. W., Carlson, N. V., Evans, N. P., Khan, N., Potvin, D. A., … & Wascher, C. A. (2023). How chronic anthropogenic noise can affect wildlife communities. Frontiers in Ecology and Evolution, 11, 289. Open Access.
• Pieniazek, R. H., Beach, R. K., Dycha, G. M., Mickle, M. F., & Higgs, D. M. (2023). Navigating noisy waters: A review of field studies examining anthropogenic noise effects on wild fish. The Journal of the Acoustical Society of America, 154(5), 2828-2842. Open Access.

Where to Find More Information

A searchable spreadsheet of all the relevant studies is available upon request (see contact information below) or on our website. The spreadsheet will be updated annually, and an annual briefing document will be prepared and appended to this summary. The results will be shared with the NPS community and archived on our website. 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.

Project Contacts

Cathleen Balantic, PhD; Sharolyn Anderson, PhD. Natural Resource Stewardship and Science Directorate, Natural Sounds and Night Skies Division. Email: [e-mail]

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.

Alternative text for Figure 1:

(clockwise from top left) 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 vessel and bears on a nearby beach.

Alternative text for Figures 2 and 4:

• 1978: 9 human response studies;
• 1979: 9 human response studies;
• 1980: 8 human response studies;
• 1981: 8 human response studies;
• 1982: 5 human response studies;
• 1983: 12 human response studies; 1 wildlife response study;
• 1984: 4 human response studies;
• 1985: 5 human response studies;
• 1986: 2 human response studies;
• 1987: 7 human response studies;
• 1988: 7 human response studies;
• 1989: 4 human response studies;
• 1990: 5 human response studies; 1 wildlife response study;
• 1991: 8 human response studies; 1 review-human study;
• 1992: 2 human response studies;
• 1993: 6 human response studies; 1 wildlife response study;
• 1994: 10 human response studies;
• 1995: 6 human response studies; 1 wildlife response study;
• 1996: 15 human response studies; 2 wildlife response studies;
• 1997: 13 human response studies; 1 review-human study;
• 1998: 8 human response studies; 1 wildlife response study;
• 1999: 14 human response studies; 2 wildlife response studies;
• 2000: 11 human response studies;
• 2001: 10 human response studies; 1 review-human study;
• 2002: 11 human response studies; 1 review-human study; 3 wildlife response studies;
• 2003: 13 human response studies; 1 review-wildlife study; 7 wildlife response studies;
• 2004: 21 human response studies; 7 wildlife response studies;
• 2005: 17 human response studies; 5 wildlife response studies;
• 2006: 18 human response studies; 2 review-wildlife; 11 wildlife response studies;
• 2007: 21 human response studies; 3 review-human studies; 13 wildlife response studies;
• 2008: 23 human response studies; 1 review-wildlife studies; 6 wildlife response studies;
• 2009: 34 human response studies; 21 wildlife response studies;
• 2010: 39 human response studies; 1 review-wildlife studies; 14 wildlife response studies;
• 2011: 35 human response studies; 11 review-human studies; 2 review-wildlife studies ; 34 wildlife response studies;
• 2012: 36 human response studies; 3 review-human studies; 57 wildlife response studies;
• 2013: 45 human response studies; 1 review-human studies; 42 wildlife response studies;
• 2014: 43 human response studies; 2 review-human studies; 1 review-wildlife studies; 37 wildlife response studies;
• 2015: 55 human response studies; 3 review-human studies; 1 review-wildlife studies; 43 wildlife response studies;
• 2016: 74 human response studies; 6 review-human studies; 67 wildlife response studies;
• 2017: 59 human response studies; 5 review-human studies; 4 review-wildlife studies; 57 wildlife response studies;
• 2018: 59 human response studies; 13 review-human studies; 2 review-wildlife studies; 56 wildlife response studies;
• 2019: 78 human response studies; 5 review-human studies; 5 review-wildlife studies; 54 wildlife response studies
• 2020: 61 human response studies; 12 review-human studies; 5 review-wildlife studies; 50 wildlife response studies;
• 2021: 73 human response studies; 1 plant response study; 12 review-human studies; 8 review-wildlife studies; 71 wildlife response studies;
• 2022: 70 human response studies; 1 plant response study; 11 review-human studies; 2 review-wildlife studies; 47 wildlife response studies;
• 2023: 61 human response studies; 0 plant response studies; 6 review-human studies; 7 review-wildlife studies; 59 wildlife response studies

Alternative Text for Figure 3:

The pie charts display proportions of anthropogenic noise sources for peer reviewed studies on noise impacts to humans and wildlife from 1978 to 2023. Human studies N = 1229; Wildlife studies N = 830. For human studies, there were 301 studies on noise from generic/built sources, 2 on military noise, 2 on recreation noise, 149 on resource extraction noise, and 770 on transportation noise. For wildlife studies, there were 404 studies on noise from generic/built sources, 35 on military noise, 7 on recreation noise, 176 on resource extraction noise, and 205 on transportation noise.

Last updated: February 29, 2024