Sound Characteristics Flashcards
When the air molecules come close to each other, they form areas of high pressure
condensation/compressions
When the molecules set apart from each other, they form areas of low pressure
rarefactions
These alternating areas of successive condensations and rarefactions (alternating areas of high & low pressure) generate
“The sound wave”
The outermost wave in this sphere is
wave front
What propagate or travel is
the disturbance in the environment, not the air molecules
meaning that the motion of particles is along the direction of propagation
Sound is a longitudinal wave
the motion of the particles is perpendicular to the direction of propagation
Transverse waves
The sound wave that propagates and travels a certain distance is
incident wave
When sound waves travel through any medium, one or more of the following phenomena may occur
Transmission, Absorption, Reflection, Refraction.
When a sound wave enters another medium, there is transmission of the wave in the medium. A sound wave in air can be transmitted through a wall in a house. Or sound can enter water and be transmitted in the liquid.
Sound waves travel faster in solid than liquids and in liquids than air
Transmission
As sound travels through any medium, there is some loss due to absorption. Since sound is a regular vibration of the atoms or molecules in a material, some of the kinetic energy of the waveform is lost due to molecular collisions (friction). That sound energy is turned into random heat energy.
Absorption
When a wave bounces off an object and changes direction – this is
reflection
the bending of a wave as it passes from one medium to another.
Refraction
occurs in a situation where there are reflected waves meet with on going incident waves
Interference
An increase sound pressure at a particular point
constructive interference
A decrease in the sound pressure
Destructive interference
an acoustic phenomenon resulting from multiple reflected sound waves occur and reach the listener’s ear with minimal time delay in comparison to the incident sound waves
Reverberation
is an exaggerated form of reverberation.It occurs when the delay can be noticeable and the distance between the reflected surface and the listener’s ear is substantial
Echo
the environment in which the sound waves travel
Sound fields
There are no boundaries or barriers
Sound waves propagate indefinitely
No reflection, no diffraction, or transmission (no obstacles)
Free field
Anechoic chamber (no echo)
anechoic and soundproof (no reflection or transmission)
Obtained in reverberant room at relatively great distance from the sound source
Diffuse sound field
several wave lengths away from the sound source
far field
distances of less than a few wave lengths from the sound source
Near field
