The interference pattern produced by two waves of equal amplitude and frequency travelling in opposite directions. The pattern is characterized by alternating nodal and antinodal regions. Only the standing wave, the interaction of these two waves meeting, is stationary.
In room acoustics, an apparently stationary waveform created by multiple reflections between opposite room surfaces. At certain points along the standing wave, the direct and reflected waves cancel, and at other points the waves add together or reinforce each other. The result is that any sound produced in a room will be "coloured" by these room modes.
A pattern of oscillations in space in which the regions of maximum displacement and of zero displacement remain fixed in position.