Themes > Science > Physics > Acoustics > General Properties of Sound > Pressure Amplitude

The term amplitude refers to the amount of change of a time varying quantity. The amount that the pressure increases (or decrease) in the medium as the sound wave travels through is called the PRESSURE AMPLITUDE.  Pressure amplitude is measured in units called pascals (Pa) or megapascals (MPa).

 If we increase the pressure amplitude of an audible sound, it gets louder. In medical ultrasound, high energy, strong echoes are often called high amplitude echoes. They are typically displayed as bright dots on a B-mode two dimensional image.

(Note that frequency and amplitude represent independent features of a sound wave. In audible sound we refer to them as pitch and loudness.)


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