Acoustics



** Speed ** : It ** ' ** s the scalar quantity which is the magnitude of the velocity vector. The SI units for speed are ** m / s ** (meters per second).

** Frequency: ** The number of times a specified phenomenon occurs periodicly in a specified interval. In physics is the number of times that a periodic function or vibration repeats itself in a specified time. It is usually measured in hertz. Symbol ** ν **, //** f. **//

** Wavelength **** : ** Is the distance, measured in the direction of propagation, between two points of the same phase in consecutive cycles of a wave. Symbol ** λ **

** Longitudinal ** : Means along the length, running lengthwise, or (by extension) over the course of time. Sound is transmitted through gases, plasma, and liquids as longitudinal waves, also called compression waves. And these longitudinal waves are waves that have the same direction of oscillations or vibrations along or parallel to their direction of travel, which means that the oscillations of the medium (particle) is in the same direction or opposite direction as the motion of the wave.

** Transverse **** : ** Crossing from side to side; athwart; crossways. A transverse wave is a moving wave that consists of oscillations occurring perpendicular to the direction of energy transfer. If a transverse wave is moving in the positive x-direction, its oscillations are in up and down directions that lie in the y-z plane.


 * VIDEO: **

 **// The Sound Sources //**

//** Salford's amazing world of sounds **//

The video explains what the sound is and where it comes from, how is it produced and the different ways to get it.

Sound is caused by the vibration of objects. Big objects make large waves and lower frequency notes. Small objects on the other hand create small waves and there for higher frequency notes. If we blow something like a balloon, as we make it bigger, it goes more and more transparent, it’s because the rubber of the balloon has to spread on a bigger area, the same thing happens with the energy of sound, it has to spread over a bigger area, and there for it has to get quitter because the energy is smaller.


 * Impulsive Sound: **

A sound that lasts for a short period of time and includes frequencies over a large portion of the acoustic spectrum, such as a hammer blow or hand clap.