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Instead, the decibel is used for a wide variety of measurements in science and engineering, most prominently for sound power in acoustics, in electronics and control theory. In electronics, the gains of amplifiers, attenuation of signals, and signal-to-noise ratios are often expressed in decibels.
Sound power level (SWL) or acoustic power level is a logarithmic measure of the power of a sound relative to a reference value. Sound power level, denoted LW and measured in dB, [9] is defined by: [10] where. P is the sound power; P0 is the reference sound power; 1 Np = 1 is the neper; 1 B = 1 / 2 ln 10 is the bel;
Sound pressure level (SPL) or acoustic pressure level (APL) is a logarithmic measure of the effective pressure of a sound relative to a reference value. Sound pressure level, denoted Lp and measured in dB, [4] is defined by: [5] where
Sound intensity level (SIL) or acoustic intensity level is the level (a logarithmic quantity) of the intensity of a sound relative to a reference value. It is denoted LI, expressed in nepers, bels, or decibels, and defined by [2] where
Sound exposure level. Sound exposure level (SEL) is a logarithmic measure of the sound exposure of a sound relative to a reference value. Sound exposure level, denoted LE and measured in dB, is defined by [1] where. E is the sound exposure; E0 is the reference sound exposure; 1 Np = 1 is the neper; 1 B = 1 / 2 ln 10 is the bel;
Dynamic range (abbreviated DR, DNR, [ 1 ] or DYR[ 2 ]) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, like sound and light. It is measured either as a ratio or as a base-10 (decibel) or base-2 (doublings, bits or stops) logarithmic value of the ratio between the largest and smallest signal values. [ 3 ]
Definition. One definition of signal-to-noise ratio is the ratio of the power of a signal (meaningful input) to the power of background noise (meaningless or unwanted input): where P is average power. Both signal and noise power must be measured at the same or equivalent points in a system, and within the same system bandwidth.
Definition. Sound is defined as " (a) Oscillation in pressure, stress, particle displacement, particle velocity, etc., propagated in a medium with internal forces (e.g., elastic or viscous), or the superposition of such propagated oscillation. (b) Auditory sensation evoked by the oscillation described in (a)." [2]