It will leave the wall at the angle it hit it and carry on around the room. Oblique Modes are the hardest to explain. They involve all six surfaces of a room, and have about half the energy of Tangential Modes, one quarter of the energy of Axial modes. The measurements for the room excluding the small protruding box were: This mode looks something like the Tangential Mode, except instead of just moving around on a flat plane, it bounces off of the ceiling and floor on it’s way around. To work out the problem frequencies in a room you need to first double the height, width and length measurements to get the standing wave length on each axis. Next do the calculation, speed of sound (344m/s)÷ wavelength= fundamental frequencies. After this you would take all of the fundamental frequencies and there harmonics and put them in a table, the frequencies that occur more than once across the 3 axis are the rooms axial problem frequencies This is because the problem frequencies are the waves that stand in the room perfectly and when they overlap they create nodes e.g. (the line through the box represents the standing sound wave). Standing waves are a problem because they create hot spots in the room (nodes). Nodes are where the sound waves from all 3 axis’ intersect, at equal intervals, creating a dead spot in the room. These nodes can be along any axis in the room (any where in the room at any height at equal intervals). Standing waves look like this (the first one being the fundamental standing wave and then the next the 2nd harmonic then 3rd then 4th) The harmonics being the previous frequency plus the fundamental: Anti-Nodes is the opposite of this (affectively the gaps) where the sound is louder in certain spots of the room.
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