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, the practice of minimizing

noise pollution Noise pollution, or sound pollution, is the propagation of noise or sound with potential harmful effects on humans and animals. The source of outdoor noise worldwide is mainly caused by machines, transport and propagation systems.Senate Publi ...

reverberation In acoustics, reverberation (commonly shortened to reverb) is a persistence of sound after it is produced. It is often created when a sound is reflection (physics), reflected on surfaces, causing multiple reflections that build up and then de ...

. 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 includes not just major roads, but also other public roads and rights of way. In the United States, it is also used as an equivalent term to controlled-access highway, or ...

to reduce sound levels in the vicinity of properties. 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 running of a mathematical model on a computer, the model being designed to represent the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be determin ...

to analyze roadway noise has been available since the early 1970s. The earliest published scientific design of a noise barrier may have occurred in Santa Clara County,

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

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, Sa ...

Los Altos, California Los Altos (; Spanish language, 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 United States census, 2020 census. Most of the city's growth ...

. The county used a computer model to predict the effects of sound propagation from roadways, with variables consisting of

vehicle A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered land vehicle, human-powered vehicles (e.g. bicycles, tricycles, velo ...

speed 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 non-negative scalar quantity. Intro ...

, ratio of trucks to automobiles, road surface type, roadway geometrics, micro-

meteorology Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agricultur ...

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 to present experiences of a real or imagined event before a live audience in a specific place, often a Stage (theatre), stage. The performe ...

, conference rooms 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 in Cambridge, Massachusetts. In 1966, the Franklin Institute awarded the firm the Frank P. Brown Medal, in 1999 BBN received the ...

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, 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 construction, constructi ...

and

materials science Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials sci ...

. Sound baffles are also used in speaker cabinets to absorb

energy Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...

from the pressure created by the speakers, thus reducing cabinet

resonance Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximu ...

. 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 Student transport, transport students to and from school or school-related activities, but not including a charter ...

driver in

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

, won a new school bus in a national contest held by Wayne Corporation for the suggestion that sound baffles be installed in the ceiling of school buses. In 1981, they were first made mandatory by the

state of California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

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