Chapter 1 Sound Reinforcement Flashcards
Sound is technically called _______.
acoustical energy
Acoustical energy is the pushing and pulling of a _____.
physical / medium (usually air)
A complete wave cycle is 1/2 cycle of ____, followed by 1/2 cycle of ____.
compression / rarefraction
A rate of ___ is called the frequency.
fluctuations
To be called sound, the frequency must be between ____ cycles per second (cps)
20 and 20,000
The unit of frequency is ___.
Hertz (Hz) 20 Hz = 20cps
Sound waves travel through air at ___.
1130 ft/second (at sea level and temp of 59 degree F
___ is independent of frequency.
Speed of sound
Physical measurement of a wave is the ___. Wavelength = ____
wavelength / speed/frequency
An ___ is an electrical version of sound; audio equipment, the ___ or ___ fluctuates at the same rate as the accoustical energy.
audio signal
voltagee
current
The amplitude or strength of an audio signal is called the ____.
signal level
Relationship between a wave and known time reference is called the ____.
phase
___ is expressed in degrees. One complete cycle of a ___ equals 360 degrees.
phase / sine wave
___ is very important in sound systems. Phase must be controlled because it effects how sounds add together.
Phase
When ___ are mixed in a console or in the air, they add algebraically.
audio signals
A sound system is a system of electronic components that’s designed to amplify sound. Name the three most common reasons.
Help people hear better.
Make sound louder for artistic reasons.
Enable people to hear sounds in remote locations.
Sound systems convert ___ energy into ___ energy, modifying the ___ energy and then converting it to ___ energy.
acoustic / electrical / acoustic
In audio electronics, devices that convert energy from one form into another are called ___. Devices that change one or more aspects of an audio signal are called ___.
transducers
signal processors
Input transducers convert ___ energy into ___ energy; then signal processors alter one or more characteristics of the ___. Output transducers convert the ___ energy (amplified for otherwise processed) back into acoustic energy.
acoustic / electrical / audio signal / electrical
Examples of input transducers
Air pressure or velocity microphones, contact pickups, magnet pickups, tape heads, phonograph pickups (cartridges), lazer pickups, optical pickups.
Examples of output transducers
woofer, midrange, tweeter, full range, subwoofer, supertweeter, monitor, and headphones
Name the three devices that make up a basic model of sound system.
Input transducers (microphones), signal processing (mixing console -> power amplifiers) output transducers (loudspeakers)
___ describes the relationship between a device’s input and output with regard signal frequency and amplitude, gives the usable range of signal frequencies for a device.
frequency response
What’s the range and tolerance of 30Hz to 18Hz, +3dB?
Range for 30Hz to 18Hz, tolerance 3dB (maximum expected deviation between output and input over the range).
