I recently started reading about the topic "Waves" and started learning it from Transverse Waves. After building enough intuition I moved on to longitudinal waves especially sound waves. While reading the same from "The Concepts of Physics-by H. C Verma", I came across the following part:
The fact that displacement is 0 where the pressure change is maximum and vice versa puts the 2 descriptions on different footings. The human ear or an electronic detector responds to the change in pressure and not to the displacement in a straight forward way.
Further more the author quoted and example of 2 loud speakers facing each other and a detector at the midpoint. The displacement of the particle at the detector is 0, however the pressure increases simultaneously in both directions. The detector would sense the pressure change and detect sound, though displacement of the particles is zero.
I could vaguely understand it, but could not form a solid idea about the same. A longitudinal wave is just the movement of particles about their mean (in the direction of wave propagation). However I couldn't intuitively think how a wave could possibly exist without the movement of particles at that point. Like in case of a standing Transverse wave, I could touch a node and not sense waves at work. But I cannot form a solid idea of why a detector could sense a wave without a wave existing in the first place at that point? Please tell me for some clarifications as I am rather confused about it myself.