Our world is noisy—from lawnmowers, cars, and other anthropogenic sounds in rural areas to the train, plane, and traffic noise in urban environments. But even if you’ve grown accustomed to hearing the cacophony of city life or the intermittent screech of aircraft overhead, noise pollution is more than just a nuisance; it can harm your health.

Last year, an interactive article from the New York Times detailed some of the adverse health effects of chronic noise exposure, highlighting how high levels of sound and sudden loud noises can impact the human body and mind. Similar to air pollution from wildfires or water pollution from runoff, noise pollution, at high enough levels, can have serious human health consequences.

But before we can discuss approaches to mitigate environmental noise, it’s crucial to understand how exactly it’s produced and the adverse effects it can have on human health.

The Science of Sound and Noise

While the terms “sound” and “noise” are often used interchangeably, not all sounds are noises. Noise is any loud or unpleasant sound that can cause anything from annoyance to hearing loss, depending on exposure and intensity. Think of “sound” as something you can measure or model and “noise” as a human response to that sound.

Generally, sound is expressed on a decibel scale where 0 decibels (dB) is the threshold for the lowest sound a human can hear. Walking through autumn leaves will expose you to around 30 dB, while a busy street will register around 60 to 70 dB. Passing by an ambulance siren or railway noise will easily exceed 100 dB.

These differences might not seem large, but decibels operate on a logarithmic scale, meaning that the relative “loudness” of a sound doubles with every 10 dB increase.

When Does Sound Become Noise Pollution?

Because limitations often depend on the length, frequency, and intensity of noises, there’s no universal threshold for what constitutes “noise pollution.” However, the World Health Organization (WHO) and the US Environmental Protection Agency (EPA) recommend avoiding continuous environmental noise exposure above 85 dB over a 1-hour period or 70 dB over a lifetime. Avoiding exposure to sounds above these levels can prevent noise-induced hearing loss and other negative physical and mental health effects. To ensure quality sleep, WHO recommends a nighttime noise level below 40 dBA, averaged over the year.

The Impacts of Noise on Human Health

While the EPA and WHO have established recommendations for average noise exposure throughout the day and at night, these guidelines do not account for the disruptive effects of a sudden loud noise.

For instance, the aforementioned New York Times article cited a Swiss study that compared the average nighttime transportation noise level of a railway versus a highway. The researchers found that while both had an 8-hour average of 55 dBA, the continuous hum of the road traffic caused less disruption than the intermittent blaring train. Moreover, they found that an increase in this “noise intermittency” was associated with a greater risk of cardiovascular disease, heart attacks, and strokes.

Exposure to excessive noise can cause a cascade of effects in the body, starting with high blood pressure and the release of the stress hormone cortisol. Over time, this can cause inflammation that increases the risk of heart disease.

Beyond the physiological effects, there are also a range of mental health effects. Noise annoyance can cause stress, difficulty sleeping, irritability, and frustration, but the long-term effects go much deeper. Studies have linked environmental noise exposure to mental health and cognitive impairment in adults, and an increase in behavioral issues in children—exacerbated by demographic and socioeconomic factors.

Noise Level Inequities

Unfortunately, noise pollution often has inequitable impacts on our communities. Many historically marginalized communities live in areas with excessive noise from transportation, construction sites, or industrial activities.

A prepandemic study of the contiguous United States found that wealthier communities are quieter than those with lower incomes (44 dBA vs. 46.9 dBA). Additionally, communities where 75% of residents were Black had higher nighttime noise levels than communities with no Black residents (46.2 dBA vs. 42.3 dBA). These levels are well within the range to cause sleep disturbance, although they likely will not lead to hearing impairment.

These disparities underscore the importance of controlling noise exposure to mitigate adverse health effects, especially in historically marginalized communities.

Mitigating Noise Pollution with Noise Control Engineering

Noise control engineering leverages specialized techniques, technologies, and tools to understand and control the noise level and sound path emitted by a specific source. In the context of noise pollution, that means:

• Evaluating environmental noise exposure across a given region.
• Modeling how sound propagates across the area.
• Testing and implementing noise reduction methods.

At RSG, we work with clients in the public and private sectors across the United States to address the growing issue of noise pollution. By collecting data and employing our advanced acoustical modeling techniques, we can estimate how noise will propagate in various environments and from a range of sources, including:

Transportation: From railways and planes to road traffic noise, transportation can carry noise as far as it carries people. Methods to reduce sounds from these sources include highway barriers, quieter pavement, and quiet zones.

Mining and Industry: Industrial processes often involve loud, heavy machinery. Reducing this kind of environmental and occupational noise exposure is crucial for employees and nearby communities.

Uncrewed Aircraft Systems (UASs): More recently, UASs, or drones, have become a viable technology for delivery companies. Noise annoyance from these craft is a focus for many communities and proponents of these technologies. We can help mitigate these complaints with an effective modeling framework that considers flight paths and existing sound maps.

RSG: Reducing Noise in the Renewable Energy Sector

As the world transitions toward a greener future, the renewable energy sector is poised to experience rapid growth over the coming years and decades.

At RSG, we’ve worked with both public and private sector clients as leading experts in noise control engineering for renewable energy projects, including solar and wind farms and battery energy storage systems (BESS).

Battery Energy Storage Systems (BESS): BESS are often integrated into renewable energy projects such as solar and wind to enhance the flexibility, reliability, and sustainability of these energy solutions. They include cooling systems, inverters, and transformers that can produce noise during operations but that can be effectively mitigated through siting and other operational strategies.

Solar Farms: Solar farms often require transformers, inverters, emergency generators, and air conditioners that all produce sound. Noise control engineering can help identify sound mitigation strategies before project construction. For instance, our work on the Wheatsborough Solar Project in Erie County, Ohio, concluded that noise mitigation efforts would reduce operational sound levels below the required threshold.

Wind Farms: Wind turbines can also cause unwanted sound, whether from the turbines themselves or the substation. Because these large-scale wind farms are typically located in rural areas, the relatively low level of sounds generated can be audible above the rural background sound levels and can annoy residents. RSG works on both research on sound generation from wind turbines and helping to site wind turbines to reduce noise impacts.

Noise Pollution: Not Just a Land Problem

Noise pollution is not just an issue above ground. While most human activity occurs on land, human aquatic operations can also generate harmful levels of noise, particularly for marine life. Underwater noise pollution can drive marine life away from a region, disrupting the food chain and even breeding grounds for some species.

Boat sounds are a common culprit, but other sound sources often come from construction projects. For example, pile driving for offshore wind turbines can be a major contributor to underwater noise pollution. This high-level sound transmits through water far more effectively than air, causing detrimental health impacts for fish and other marine life if not otherwise mitigated or minimized.

At RSG, we apply our specialized expertise and acoustical tools to understand and quantify sound in underwater environments. Using the dBSea software platform, our noise control engineers can accurately predict the propagation of underwater noise for projects. This is especially critical for clients operating within or near existing marine mammal habitats or fisheries, as construction noises can harm or kill these animals.

RSG’s Noise Control Engineering Services: Creating a Quieter World

Noise control engineering serves a pivotal role in mitigating the human health and environmental impacts of noise pollution—whether on land, in the air, or underwater.

At RSG, our noise control engineers and acousticians work with clients to understand and address the potential issues unwanted sound can pose for projects. With extensive experience and custom-developed tools for data collection and noise-level modeling, we offer solutions to minimize the impacts of sound on humans and the environment.

Reach out to us today to learn more about noise control engineering or request a consultation.