Sound-Environment Interaction Flashcards
The absorptive capability of a material is ________ and may be measured in ________
Frequency dependent, Sabins
The absorption coefficient is the fraction of acoustic energy which is ________ at a surface
Absorbed
________ refers to a bending of the sound wave because of differences in the speed of the sound wave caused by temperature gradients
Refraction
A sound shadow is the result of the inability of a sound wave to ___________ around an obstacle
Diffract
Atmospheric absorption of sound energy varies according to __________
Frequency, temperature and humidity
Atmospheric absorption is __________ for low humidity situations with hot temperatures
High
Ground absorption is generally __________ for high frequencies
Greater
______ is a singular reflection off a surface
Echo
Multiple reflections from parallel surfaces or buildings is called ___________
Canyon Effect
Ground effect refers to ___________ between the direct and reflected wave when the source and receiver are close to the ground
destructive interference
A barrier that fails to obscure “line of sight” propagation from a source may ______ sound levels
Increase
A six-foot barrier will be most effective for reducing ______frequencies, and completely ineffective for reducing ______ frequencies
High, Low
The fixed pattern of nodes in a standing wave are experienced as _________
dead spots
The fundamental resonance modes of a room are called __________
eigentones
A delayed sound, as with an echo, must occur at least ______ after the event without being masked by the original sound
50 ms
Reverberation time is the time required for the sound energy to fall to ________ its original strength after its cessation
-60 dB below
Reverberation time ________ with room size and _______ with higher absorption coefficients
Increases, decreases
Speech comprehension decreases with reverberation times great than a second due to the __________ of speech transients
masking
The ratio of direct to indirect sound in an enclosed space falls off with _________ distance from the source, with a greater percentage of the sound energy being reflected sound
Increasing
Due to their ability to _________ around obstacles, low frequency sound waves are difficult to localize
diffract
Uniform distribution of sound in a space is called ________
a diffuse sound field
A ________ is an environment with anechoic conditions because the sound energy falls off according to the square of the distance
free field
The phenomenon of ________ occurs when a moving sound source approaches and recedes from a listener
Doppler effect
According to the Doppler effect, when the speed is constant, the effect is a ________ when the source approaches and a ________ when it recedes
higher pitch, lower pitch
