Standing Waves and Room Modes

Standing waves occuring In a rectangular room are commonly called ‘Room Modes’ and Can be split into 3 categories

Axial modes – one dimensional modes occuring either along the length, width or height of the Room. Also showcased In the sketch below as a green Line. (Shown from a topview of the room)

2D Sketch of the 3 room mode types, showcasing the Tangential modes (red line) and Axial modes (green line). The third mode (Oblique modes) type is not show on the sketch.

Tangential modes – two dimensional modes occuring in two dimensions at a time as showcased In the sketch below with a red Line. In this case it is showcased along the length and width of the room.

Oblique modes – three dimensional modes occuring In all dimensions at the same time. These modes are not showcased In the sketch above.

Typically the dominant modes are the simple axial modes and the least dominant modes are the oblique modes.
One could also imagine the complexity of oblique modes to utilize all dimensions of the room and the ‘stability’ of the modes, taken into account factors like absorption and scattering.