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Soundfield Quantities of a Plane Wave − the Amplitudes

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Soundfield Quantities of a Plane Wave − the Amplitudes Soundfield Quantities of a Plane Wave – The Amplitudes German: Schallfeldgrößen einer ebenen Welle – Amplituden: http://www.sengpielaudio.com/SchallfeldgroessenEinerEbenenWelle.pdf This particle has its minimum deflection and currently moves forward. Thus, its sound particle velocity is strongly positive. This particle has reached its maximum deflection and will reverse the direction of movement. Thus, its sound particle velocity is zero. This particle has reached its minimum deflection and moves back momentarily. Thus, its sound particle velocity is strongly negative. This particle has reached its maximum deflection and will reverse the direction of movement. UdK Berlin Thus, its sound particle velocity is zero. SengpielSengpiel Position of the air 04.2009 particles at rest Schall Position of the air particles in oscillating state compression expansion compression expansion Displacement Sound particle displacement / particle deflection Amplitude Particle displacement The maximum sound pressure velocity is at the minimum of the particle velocity Amplitude of sound pressure Sound pressure RMS value8 Pressure gradient Atmospheric pressure between points 101,325 Pa r1 and r2 The time t or The maximum particle the distance r velocity is in the maximum to the source of the sound pressure can be given r = c × t (c = 343 m/s) Amplitude of the sound particle velocity Sound particle velocity RMS value Instantaneous value of the sound particle The pressure gradient velocity Amplitude of the is always the derivative pressure gradient (slope) of the particle velocity Pressure gradient RMS value Instantaneous value of the pressure gradient From: Andreas Friesecke, "Die Audio-Enzyklopädie", K.G.Saur-Verlag, München, 2007, page 26 There are different amplitudes of sound. For a plane wave, sound pressure and particle velocity are in phase. The simple equation pRMS = pa / √2, explains acoustic pressure amplitude pa (peak value) and sound pressure pRMS Amplitudes of air particle displacement , sound pressure p, sound velocity v, and pressure gradient pmean all different things as sound field quantity. Avoid the term amplitude using a sound energy quantity. Some sound engineering publications wrongly assume that particle velocity and pressure gradient are the same. All directional microphones exhibit the principle of the sound pressure difference p, called pressure-gradient, where besides the front of the microphone diaphragm more or less also the reverse side of the diaphragm is cov- ered by sound. Therefore these sensors are called pressure-gradient receivers or pressure-gradient microphones and have little to do with particle velocity v. Look also at: "What is amplitude?" http://www.sengpielaudio.com/calculator-amplitude.htm "Relationship of acoustic quantities associated with a plane progressive acoustic sound wave ": http://www.sengpielaudio.com/RelationshipsOfAcousticQuantities.pdf Johannes Kammann, "Sound particle velocity and pressure gradient are not the same (German)": http://www.sengpielaudio.com/SchallschnelleIstNichtDruckgradient.pdf Manfred Hibbing, "Sound particle velocity, pressure gradient and microphones (German)": http://www.sengpielaudio.com/SchallschnelleDruckgradientMikrofone-HibbingMails.pdf .
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