A sound baffle is a construction or device which reduces the strength (level) of airborne sound. Sound baffles are a fundamental tool of

noise mitigation Noise control or noise mitigation is a set of strategies to reduce noise pollution or to reduce the impact of that noise, whether outdoors or indoors. Overview The main areas of noise mitigation or abatement are: transportation noise control, ...

, the practice of minimizing

noise pollution Noise pollution, also known as environmental noise or sound pollution, is the propagation of noise with ranging impacts on the activity of human or animal life, most of them are harmful to a degree. The source of outdoor noise worldwide is main ...

reverberation Reverberation (also known as reverb), in acoustics, is a persistence of sound, after a sound is produced. Reverberation is created when a sound or signal is reflected causing numerous reflections to build up and then decay as the sound is abso ...

. An important type of sound baffle is the

noise barrier A noise barrier (also called a soundwall, noise wall, sound berm, sound barrier, or acoustical barrier) is an exterior structure designed to protect inhabitants of sensitive land use areas from noise pollution. Noise barriers are the most effecti ...

constructed along

highways A highway is any public or private road or other public way on land. It is used for major roads, but also includes other public roads and public tracks. In some areas of the United States, it is used as an equivalent term to controlled-access ...

to reduce sound levels at properties in the vicinity. Sound baffles are also applied to walls and ceilings in building interiors to absorb sound energy and thus lessen reverberation.

Highway noise barriers

The technology for accurate prediction of the effects of noise barrier design using a

computer model Computer simulation is the process of mathematical modelling, performed on a computer, which is designed to predict the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be deter ...

to analyze

roadway noise Roadway noise is the collective sound energy emanating from motor vehicles. It consists chiefly of road surface, tire, engine/transmission, aerodynamic, and braking elements. Noise of rolling tires driving on pavement is found to be the biggest ...

has been available since the early 1970s. The earliest published scientific design of a noise barrier may have occurred in

Santa Clara County Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259, as of the 2020 United States Census, 2020 census. Santa Clara County and neighboring Sa ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

in 1970 for a section of the

Foothill Expressway There are 21 routes assigned to the "G" zone of the California Route Marker Program, which designates county routes in California. The "G" zone includes county highways in Monterey County, California, Monterey, San Benito County, California, San ...

Los Altos, California Los Altos (; Spanish for "The Heights") is a city in Santa Clara County, California, in the San Francisco Bay Area. The population was 31,625 according to the 2020 census. Most of the city's growth occurred between 1950 and 1980. Originally a ...

. The county used a computer model to predict the effects of sound propagation from

roadways A carriageway (British English) or roadway (North American English) consists of a width of road on which a vehicle is not restricted by any physical barriers or separation to move lateral movement, laterally. A carriageway generally consists of ...

, with variables consisting of

vehicle A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), wa ...

speed In everyday use and in kinematics, the speed (commonly referred to as ''v'') of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a scalar quanti ...

, ratio of trucks to automobiles, road surface type, roadway

geometric Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is ca ...

s, micro-

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not ...

and the design of proposed soundwalls.

Interior sound baffle design

Since the early 1900s, scientists have been aware of the utility of certain types of interior coatings or baffles to improve the

acoustics Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician ...

concert halls A concert hall is a cultural building with a stage that serves as a performance venue and an auditorium filled with seats. This list does not include other venues such as sports stadia, dramatic theatres or convention centres that may ...

theaters Theatre or theater is a collaborative form of performing art that uses live performers, usually actors or actresses, to present the experience of a real or imagined event before a live audience in a specific place, often a stage. The perform ...

conference rooms A conference hall, conference room, or meeting room is a room provided for singular events such as business conferences and meetings. Room It is commonly found at large hotels and convention centers though many other establishments, including even ...

and other spaces where sound quality is important. By the mid-1950s,

Bolt, Beranek and Newman Raytheon BBN (originally Bolt Beranek and Newman Inc.) is an American research and development company, based next to Fresh Pond in Cambridge, Massachusetts, United States. In 1966, the Franklin Institute awarded the firm the Frank P. Brown ...

and a few other U.S. research organizations were developing technology to address sound quality's design challenges. This design field draws on several disciplines including

acoustical science Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician ...

, computer modeling,

architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing building ...

and materials science. Sound baffles are also used in

speaker cabinets A loudspeaker enclosure or loudspeaker cabinet is an enclosure (often rectangular box-shaped) in which speaker drivers (e.g., loudspeakers and tweeters) and associated electronic hardware, such as crossover circuits and, in some cases, power ...

to absorb

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...

from the pressure created by the speakers, thus reducing cabinet

resonance Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...

. In 1973, Pearl P. Randolph, a

school bus A school bus is any type of bus owned, leased, contracted to, or operated by a school or school district. It is regularly used to transport students to and from school or school-related activities, but not including a charter bus or transit bus ...

driver in

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

, won a new school bus in a national contest held by

Wayne Corporation The Wayne Corporation was an American manufacturer of buses and other vehicles under the "Wayne" marque. The corporate headquarters were in Richmond, Indiana, in Wayne County, Indiana. During the middle 20th century, Wayne served as a leading p ...

for the suggestion that sound baffles be installed in the ceiling of

school buses A school bus is any type of bus owned, leased, contracted to, or operated by a school or school district. It is regularly used to transport students to and from school or school-related activities, but not including a charter bus or transit bus ...

. In 1981, they were first made mandatory by the

state of California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

Vehicle exhaust sound baffles

Baffles are also found in the exhaust pipes of vehicles, particularly motorcycles.

References

{{DEFAULTSORT:Sound Baffle Ceilings Noise pollution Noise control

Highway noise barriers

Interior sound baffle design

Vehicle exhaust sound baffles

See also

References