Thursday, March 27, 2014

Amelia Rosen | Assignment 5 | Acoustics

Acoustics is the branch of physics concerned with the properties of sound, such as frequency, tone, pitch, volume, etc.  However, acoustics literally refers to the properties or qualities of a room or building that determine how sounds are transmitted in it – the degree to which sound is accounted for and controlled in a space.

Sound is a vibration.  Sound travels through air and space and produces pressure variations that the human ear translates into auditory oscillations.  These vibrations can be either erratic or regular, thus creating either noise or specific tones, respectively.

When sound or noise leaves a source, it travels in waves that fluctuate and bend depending on the speed, decibel, and force the sound was produced with.  These waves naturally change when interrupted, so within an acoustic space, it would not be smart to have a wall between the music/sound source and the audience.  The most important features to take into account when designing for acoustics are the walls and the ceiling, since these surfaces are the primary locations of potential sound reverberation.

Generally speaking, there are numerous details and elements that can change the way sound travels and is received by an audience, such as the shape of the space, the materials that make up the surrounding surfaces, and the size of the space.  When sound strikes a surface, some of it is absorbed, some of it is reflected, and some of it is transmitted through the surface.  If a surface is dense, sound will isolate well but will also reflect back into the room.  If a surface is more porous, it will absorb the sound well but will not isolate it.  In order to stop sound from travelling through a building’s structure, you must isolate it, through the use of dense rubber, adding mass, decoupling (such as by trapping air), or using airtight construction.  The materials of the ceiling and the walls of an acoustic space determine the degree that the sound reverberates which can effect how enjoyable that sound is.


Sounds are best received when evenly dispersed throughout a space, which can result from an intentional lack of large flat surfaces that simply reflect the sound at the people.  In addition, sound tends to bounce back and forth between hard, parallel surfaces, so it is common among theater and concert hall designers to use acoustic paneling that is either varied in terms of which direction they are facing or how far the are placed from the stage, such as stage 3 of the Harris Center for the Arts shown below; it is also common to use undulating surfaces, such as the one in the home cinema depicted at the end of this post.



On another note, here's a funny cartoon:


...lol

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