helirõhule
Helirõhule, often translated as sound pressure, is a fundamental physical quantity describing the intensity of a sound wave. It is defined as the difference between the pressure of the medium and the ambient pressure, caused by the passage of a sound wave. Helirõhule is measured in pascals (Pa), which is the unit of pressure. The human ear is sensitive to a wide range of helirõhule levels, from the threshold of hearing (around 20 micropascals) to the threshold of pain (around 20 pascals).
Because the range of helirõhule is so vast, it is commonly expressed on a logarithmic scale called