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Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by 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). [1]
Make Listening Safe is promoting the development of features in PLS to raise the users' awareness of risky listening practices. In this context, the WHO partnered with the International Telecommunication Union to develop suitable exposure limits for inclusion in the voluntary H.870 safety standards on "Guidelines for safe listening devices/systems."
The first research on the topic of how the ear hears different frequencies at different levels was conducted by Fletcher and Munson in 1933. Until recently, it was common to see the term Fletcher–Munson used to refer to equal-loudness contours generally, even though a re-determination was carried out by Robinson and Dadson in 1956, which became the basis for an ISO 226 standard.
Several countries and states have made it illegal to wear headphones while driving or cycling. [13] It is not uncommon to get a pressure-like feeling when using noise-cancelling headphones initially. This is caused by the lack of low-frequency sounds as being perceived as a pressure differential between the inner and outer ear. [14] [15] [16]
Within the chart “close”, “open”, “mid”, “front”, “central”, and “back” refer to the placement of the sound within the mouth. [3] At points where two sounds share an intersection, the left is unrounded, and the right is rounded which refers to the shape of the lips while making the sound. [4]
Surface weather prognostic charts for mariners indicate the positions of high and low pressure areas, as well as frontal zones, up to five days into the future. Surface wind direction and speed is also forecast on this type of chart. Wave prognostic charts show the expected sea state at some future time. [2]
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Example reading: 1 Pa = 10 −5 bar = 1 ... Template documentation Usage. See also ... Category:Pressure This page was last edited on 14 April 2024, at 00:27 (UTC ...