Sound pressureIn acoustics, sound pressure or acoustic pressure is the pressure difference between the ambient (average or equilibrium) atmospheric pressure and that of a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone. The SI unit of sound pressure is the pascal (Pa). Mathematical definitionA sound wave in a transmission medium causes a deviation (sound pressure, a dynamic pressure) in the local ambient pressure, a static pressure.
DecibelThe decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 10 (approximately 1.26) or root-power ratio of 10 (approximately 1.12). The strict original usage above only expresses a relative change.
Pascal (unit)The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m). It is also equivalent to 10 barye (10 Ba) in the CGS system.
Noise pollutionExcessive displeasing noise A Qantas Boeing 747-400 passes close to houses shortly before landing at London Heathrow Airport. Traffic is the main source of noise pollution in cities like São Paulo.
Diaphragm (acoustics)In the field of acoustics, a diaphragm is a transducer intended to inter-convert mechanical vibrations to sounds, or vice versa. It is commonly constructed of a thin membrane or sheet of various materials, suspended at its edges. The varying air pressure of sound waves imparts mechanical vibrations to the diaphragm which can then be converted to some other type of signal; examples of this type of diaphragm are found in microphones and the human eardrum.
AcousticsAcoustics is a branch of continuum mechanics 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 while someone working in the field of acoustics technology may be called an acoustical engineer.
MicrophoneA microphone, colloquially called a mic (), or mike, is a transducer that converts sound into an electrical signal. Microphones are used in telecommunication, sound recording, broadcasting, and consumer electronics, including telephones, hearing aids, and mobile devices. Several types of microphone are used today, which employ different methods to convert the air pressure variations of a sound wave to an electrical signal.
Aircraft noise pollutionAircraft noise pollution refers to noise produced by aircraft in flight that has been associated with several negative stress-mediated health effects, from sleep disorders to cardiovascular disorders. Governments have enacted extensive controls that apply to aircraft designers, manufacturers, and operators, resulting in improved procedures and cuts in pollution.
VoltThe volt (symbol: V), named after Alessandro Volta, is the unit of measurement of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). DefinitionOne volt is defined as the electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points.
Root mean squareIn mathematics, the root mean square (abbrev. RMS, rms or rms) of a set of values is the square root of the set's mean square. Given a set xi{\displaystyle x_{i}}, its RMS is denoted as either xRMS{\displaystyle x_{\mathrm {RMS} }} or RMSx{\displaystyle \mathrm {RMS} _{x}}. The RMS is also known as the quadratic mean (denoted M2{\displaystyle M_{2}}), a special case of the generalized mean.
SignalA signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields, including signal processing, information theory and biology. In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers.*As an Amazon Associate I earn from qualifying purchases.