sound pressure: the difference between the instantaneous pressure at a point in a sound field and the average pressure at that point
process: a sustained phenomenon or one marked by gradual changes through a series of states
round-leaved rein orchid: orchid having a raceme of large greenish-white flowers on a single flower stalk growing between two elliptic or round basal leaves lying on the ground; from northern Oregon and Montana across Canada to the eastern United States