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Such large measurement ranges are conveniently expressed in logarithmic scale: the base-10 logarithm of 10 12 is 12, which is expressed as a sound intensity level of 120 dB re 1 pW/m 2. The reference values of I and p in air have been chosen such that this corresponds approximately to a sound pressure level of 120 dB re 20 μPa.
I is the sound intensity; I 0 is the reference sound intensity; 1 Np = 1 is the neper; 1 B = 1 / 2 ln(10) is the bel; 1 dB = 1 / 20 ln(10) is the decibel. The commonly used reference sound intensity in air is [5] = /. being approximately the lowest sound intensity hearable by an undamaged human ear under room conditions.
While 1 atm (194 dB peak or 191 dB SPL) [11] [12] is the largest pressure variation an undistorted sound wave can have in Earth's atmosphere (i. e., if the thermodynamic properties of the air are disregarded; in reality, the sound waves become progressively non-linear starting over 150 dB), larger sound waves can be present in other atmospheres ...
A dynamic microphone is able to withstand high sound intensity and can have a dynamic range of up to 140 dB. Condenser microphones are also rugged but their dynamic range may be limited by the overloading of their associated electronic circuitry. [ 29 ]
Sound power or acoustic power is the rate at which sound energy is emitted, reflected, transmitted or received, per unit time. [1] It is defined [2] as "through a surface, the product of the sound pressure, and the component of the particle velocity, at a point on the surface in the direction normal to the surface, integrated over that surface."
A change of one bel in the level corresponds to a 10× change in power, so when comparing power quantities x and y, the difference is defined to be 10×log 10 (y/x) decibel. With root-power quantities, however the difference is defined as 20×log 10 (y/x) dB. [3]
The sound energy density level gives the ratio of a sound incidence as a sound energy value in comparison to the reference level of 1 pPa (= 10 −12 pascals). [2] It is a logarithmic measure of the ratio of two sound energy densities. The unit of the sound energy density level is the decibel (dB), a non-SI unit accepted for use with the SI ...
The plots at the bottom show the signal intensity in the indicated row of the image (red: original signal, blue: with noise). Signal-to-noise ratio ( SNR or S/N ) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise .