Acoustics

Aula Magna, Universidad Central de Venezuela. Odeon of herodes Atticus, amphitheater on the south slope of Athenian Acropolis.

==Since acoustics deals with sound, let´s find out what __S O U N D __ is. ==

= =  Speed: is the distance travelled in unit time **(m/s).** In other words, the rate at which something moves or travels; the rate at which something happens or is done.  Frequency: is the number of complete cycles in one second **(Hz).** It is the quality of occurring regularly; rate at which a function reoccurs.  Wavelenght: distance between matching points on the wave **(m);** The distance between one peak or crest of a wave of light, heat, or other energy and the next corresponding peak or crest.

 Longitudinal: vibration parallel to direction of travel of wave. Longitudinal waves travel in the direction of the length; running lengthwise.

 Transverse: vibration at right angle to direction of travel of wave. Situated or lying across; crosswise.
 * VIDEO NOTES **

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 * Sound is normally caused by vibrating objects.
 * At the beginning Salford talks about the fact that we can study sound better, when we slow down the picture to see vibrations. He also mentions that large objects that create large wavelength create sounds of low pitch or low frequency while small objects create small wavelength and low pitch sounds.
 * Then he describes how sound energy, when spread in a bigger area, gets smaller. He puts the analogal example of blowing an air ballom and how it becomes transparent as the rubber extends.
 * Acceleration noise occurs when air is compressed, for example when we clap our hands. What we hear is an acoustic wave sound of the vibration of the hands.
 * <span style="color: rgb(255, 195, 0); font-size: 140%;">Shock waves are sounds created by air compressed in high preasures.

<span style="font-size: 150%; background-color: rgb(0, 0, 0); color: rgb(0, 255, 255);">Notes from the information pages about acoustics <span style="font-size: 120%; color: rgb(255, 113, 0);"> > - Added absorption and where it is placed, > - The quantity and placing of sound-scattering objects such as furniture, shelves etc. > - The size and shape of the room > - Early sound reflections in relation to late sound reflections. > - Background noise.
 * <span style="font-size: 120%; color: rgb(57, 134, 208);">Reverberance is linked to the speed at which sound energy disappears in a room.
 * <span class="Normal" style="color: rgb(255, 255, 0);">Sound transmission, sound absorption, sound reflection and sound diffusion are all aspects of room acoustics.
 * <span style="font-size: 120%; color: rgb(128, 0, 128);">Room acoustics are about the way in which sound behaves in a room.
 * <span class="Normal" style="color: rgb(163, 31, 31);">The interaction between the person, the room and the activity decides the room acoustic comfort.
 * <span style="font-size: 120%; color: rgb(255, 113, 0);"> In many environments where people are present and communicate, high sound levels are perceived as one of the most disturbing factors.
 * <span class="Normal" style="color: rgb(0, 255, 0);">High noise levels have a negative effect on us.
 * <span style="font-size: 120%; color: rgb(0, 0, 128);"> The reverberation time is decided by:
 * <span class="Normal" style="color: rgb(255, 0, 132);">The sound level is essentially determined by the amount of absorption.
 * <span style="font-size: 120%; color: rgb(98, 39, 170);"> Clarity of speech is essentially determined by:
 * <span style="font-size: 120%; color: rgb(94, 197, 17);">The ceiling’s sound absorbing properties are described in sound absorption classes (A-E) in an international standard.
 * <span style="font-size: 120%; color: rgb(94, 197, 17);">Class A is the highest level of sound absorption.
 * <span style="font-size: 120%; color: rgb(255, 0, 0);">Effective, sound-absorbing ceilings (Sound absorption class A) affect reverberation time, sound level, speech clarity and spatial decay, thus creating good room acoustic comfort.