The diagram below uses the coils of a spiral spring to represent the individual molecules of a sound conductor. The conductor molecules are influenced by the adjacent molecules in the same way in which the coils of a spiral spring also influence each other. The sound source in the models is on the left. The compression generated by the sound source spreads as each adjacent coil of the spiral spring presses against the next one. It is important to observe that, while the wave travels from one end of the spiral to the other, the individual spirals remain in their relative position, being positioned first in one way and then in the other when the sound wave passes through. As a result, each spiral is initially part of a compression when it is pressed against the adjacent spiral and then part of a refraction when it recedes from the adjacent spiral. In the same way, all points in the sound conductor are alternately subject to compression then rarefaction. In the compression area, the pressure is positive. In the rarefaction area, the pressure is negative.