Elements of Acoustics Flashcards
____ is how the energy is generated; in other words, the source of the sound.
A. Production B. Propagation C. Control D. Interaction E. Reception
A. Production
____ is the pathway of the energy.
A. Production B. Propagation C. Control D. Interaction E. Reception
B. Propagation
____ is how (sound) energy is generated and subsequently propagated.
A. Production B. Propagation C. Control D. Interaction E. Reception
C. Control
____ is how material responds to the sound energy imposed upon it.
A. Production B. Propagation C. Control D. Interaction E. Reception
D. Interaction
____ is how hearers’ ears and brains will respond to the stimuli placed upon them.
A. Production B. Propagation C. Control D. Interaction E. Reception
E. Reception
_____ is the distance between two corresponding points of two consecutive cycles.
Wavelength
The speed of sound in air is ____ft per second.
1,130 ft (344 m)
Wavelength formula
λ = v/f
where:
• λ is the wavelength measured in feet or meters.
• v is the speed of sound in feet (meters) per second.
• f is the frequency in hertz.
divide the speed of sound by frequency
As frequency increases, the wavelength ____.
decreases
The unit for sound power is _____.
watts per square meter (W/m2)
_____ is the distance of a particle’s movement from its equilibrium position in a medium as it transmits a sound wave.
Particle Displacement
_____ is sound that arrives directly from the source to the listener.
Direct sound
____ is sound that arrives to the listener after the direct sound as reflected energy.
reflections
____ reflections bounce directly off a surface like light bouncing off a mirror. Like light, the incoming angle (the angle of incidence) will equal the outgoing angle (the angle of reflection).
Direct (or specular)
____ is the scattering or random redistribution of a sound wave from a surface. It occurs when surfaces are at least as long as the sound wavelengths but not more than four times as long.
Diffusion
For reflecting surfaces to function as diffusers, they must be heavily textured and irregular—the dimensions of irregularities should be _____ to the wavelength of sound.
nearly equal
A _____ is a series of reflections that continue to bounce back and forth between parallel hard surfaces, such as large walls, ceilings, windows, and floors.
flutter echo
A ____ is the amount of energy at fixed positions within a room. They significantly affect the perceived low-frequency performance in smaller rooms, such as boardrooms, conference rooms, classrooms, home theaters, music practice rooms, and small studios—really, any relatively small room.
mode (or standing wave or room resonance)
A _____ occurs when a sound wave travels between two reflecting surfaces, such as two parallel walls.
standing wave
_____is the sound that persists in a room after the energy that created it is stopped.
Reverberation
The _____ of a space (Figure 11-8) is said to be the number of seconds it takes for the sound to decay to one-thousandth of its original level, or 60 dB.
reverberation time
Reverberation time is also referred to as _____.
RT 60
The _____ takes an average of the four middle test frequencies (250, 500, 1000, and 2000).
noise reduction coefficient (NRC)
Generally speaking, NRC values smaller than ___ are considered to be reflective, while values greater than ___ are considered to be absorptive.
0.20 / 0.40
