What are nodes and antinodes in a standing sound wave?

In the study of acoustics, a standing sound wave is a stationary oscillation formed by the interference of two identical waves traveling in opposite directions. Within this wave, nodes and antinodes represent specific points of displacement or velocity:1234

• Nodes: These are positions where the medium (such as air) remains at zero displacement or velocity at all times. They occur due to destructive interference, where the two wave trains are always in opposition. In a closed tube, a velocity node occurs at the closed end because the air cannot move.34125
• Antinodes: These are positions of maximum displacement or velocity. They occur where the waves reinforce each other. In an open tube, a velocity antinode typically occurs at the open end, allowing for the free movement of air.34125

It is important to note that these terms can also describe pressure variations; in such cases, the locations of nodes and antinodes are reversed compared to displacement or velocity representations.3