Relevant information and concepts

Relevant information / concepts

Reflection:
When a wave reaches the boundary between one medium another medium, a portion of the wave undergoes reflection and a portion of the wave undergoes transmission across the boundary. The amount of reflection is dependent upon the dissimilarity of the two medium. Thus, a hard material such as concrete is as dissimilar as can be to the air through which the sound moves; subsequently, most of the sound wave is reflected by the walls and little is absorbed. Walls and ceilings of concert halls are made softer materials such as fiberglass and acoustic tiles. These materials are more similar to air than concrete and thus have a greater ability to absorb sound. This gives the room more pleasing acoustic properties.

Diffraction:
Diffraction is the bending of waves around small obstacles and the spreading out of waves beyond small openings. Important parts of our experience with sound involve diffraction. The most common one is that we are able to hear things around corners, due to both diffraction and reflection of sound waves happening. Diffraction in such cases helps the sound to "bend around" the obstacles.
Diffraction also causes sound waves to spread out past small openings. This aspect of diffraction also has many implications. This allows people to hear sounds inside a room even if they are outside, this spreading out of sound waves has its bad sides as it causes problem when attempts to make a room soundproof.

Wave interference:
Wave interference is when one wave completely destroys another wave when they overlap, resulting in no sound at all. This can occur either due to the waves themselves or due to the special shape of the studio which makes the waves overlaps each other through reflection, diffraction.
Imagine two different waves, one with amplitude of +1 and another -1 moving towards each other, the two pulses will completely destroy each other when they overlap, resulting in no sound that can be heard, unless the two waves themselves cannot be heard originally, just like the process of neutralization except there's no water produced.