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A graph of the A-, B-, C- and D-weightings across the frequency range 10 Hz – 20 kHz Video illustrating A-weighting by analyzing a sine sweep (contains audio). A-weighting is a form of frequency weighting and the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. [1]
dB(K) – decibels relative to 1 K; used to express noise temperature. [67] dB K⁻¹ or dB /K dB(K⁻¹) – decibels relative to 1 K⁻¹. [68] — not decibels per Kelvin: Used for the G / T (G/T) factor, a figure of merit used in satellite communications, relating the antenna gain G to the receiver system noise equivalent temperature T.
A-weighted decibels are abbreviated dB(A) or dBA. When acoustic ( calibrated microphone) measurements are being referred to, then the units used will be dB SPL ( sound pressure level ) referenced to 20 micropascals = 0 dB SPL.
OSHA's PEL for noise exposure is 90 decibels (dBA) for an 8-hour TWA. Levels of 90-140 dBA are included in the noise dose. [4] PEL can also be expressed as 100 percent “dose” for noise exposure. When the noise exposure increases by 5 dB, the exposure time is cut in half. [5] According to OSHA, a 95dBA TWA would be a 200 percent dose. [6]
Sound exposure level (SEL) is a logarithmic measure of the sound exposure of a sound relative to a reference value. Sound exposure level, denoted L E and measured in dB, is defined by [1]
The noise power from a simple load is equal to kTB, where k is the Boltzmann constant, T is the absolute temperature of the load (for example a resistor), and B is the measurement bandwidth. This makes the noise figure a useful figure of merit for terrestrial systems, where the antenna effective temperature is usually near the standard 290 K ...
dBc (decibels relative to the carrier) is the power ratio of a signal to a carrier signal, expressed in decibels.For example, phase noise is expressed in dBc/Hz at a given frequency offset from the carrier. dBc can also be used as a measurement of Spurious-Free Dynamic Range between the desired signal and unwanted spurious outputs resulting from the use of signal converters such as a digital ...
Effective perceived noise in decibels (EPNdB) or Effective Perceived Noise Level (EPNL) is a measure of the relative noisiness of an individual aircraft pass-by event. It is used for aircraft noise certification and applies to an individual aircraft, not the noise exposure from an airport.