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Examples of sound pressure in air at standard atmospheric pressure; Source of sound Distance Sound pressure level [a] (dB SPL) Shock wave (distorted sound waves > 1 atm; waveform valleys are clipped at zero pressure) [11] [12] >1.01×10 5 >191 Simple open-ended thermoacoustic device [14] [clarification needed] 1.26×10 4: 176 1883 eruption of ...
where p rms is the root mean square of the measured sound pressure and p ref is the standard reference sound pressure of 20 micropascals in air or 1 micropascal in water. [34] Use of the decibel in underwater acoustics leads to confusion, in part because of this difference in reference value. [35] [36]
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]
A sound with a loudness of 1 sone is judged equally loud as a 1 kHz tone with a sound pressure level of 40 decibels above 20 micropascals. [1] The phon is psychophysically matched to a reference frequency of 1 kHz. [2] In other words, the phon matches the sound pressure level in decibels of a similarly perceived 1 kHz pure tone. [3]
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 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 ...
Sound level meters are commonly used in noise pollution studies for the quantification of different kinds of noise, especially for industrial, environmental, mining and aircraft noise. [2] [3] The current international standard that specifies sound level meter functionality and performances is the IEC 61672-1:2013. However, the reading from a ...
The STC number is derived from sound attenuation values tested at sixteen standard frequencies from 125 Hz to 4000 Hz. These Transmission Loss values are then plotted on a sound pressure level graph and the resulting curve is compared to a standard reference contour provided by the ASTM. [11]