# Shared Flashcard Set

## Details

Sound/Frequencies
N/A
41
Engineering
09/23/2014

## Additional Engineering Flashcards

Term
 what is sound?
Definition
 waves of varying pressure in a given medium, alternating compression and rarefaction
Term
 what is (a) frequency?
Definition
 rate at which a periodic wave repeats
Term
 what is frequency measured in?
Definition
 Hertz, or "cycles per second"
Term
 lower sounds = _________higher sounds = _________
Definition
 fewer cycles; more cycles
Term
 range of human hearing
Definition
 20 Hz - 20,000 Hz
Term
 propagation of sound
Definition
 movement of sound through air or other medium
Term
 what is the opposite of a sine wave?
Definition
 white noise from a random signal generator (constant spectral density)
Term
 what is an octave?
Definition
 double frequency of original pitch
Term
 what is pink noise?
Definition
 similar to white noise, weighted towards the low end of the spectrum as opposed to no weight in white noise. warmer, quieter, lower
Term
 what are overtones?
Definition
 not naturally vibrating material produces a simple sine wave
Term
 what is the harmonic series?
Definition
 any vibrating string also vibrates at the octave above it, and the octave above that, ect ect.
Term
 vowels are _______consonants are _______
Definition
 harmonic; transients/sound structures
Term
 what is timbre?
Definition
 harmonic content that defines the characteristic of a sound
Term
 what is amplitude?
Definition
 represents air compression and rarefaction
Term
 compression goes ______ and rarefaction goes ______
Definition
 up; down
Term
 what unit is used to measure amplitude?
Definition
 decibel
Term
 what is a decibel?
Definition
 logarithmic unit used to express the ratio between two values of physical quantity, often power or intensity.
Term
 why is the decibel used?
Definition
 itâ€™s a versatile scale that possesses the logarithmic structure that makes it easy to render ratios of great difference
Term
 what is the decibel used for?
Definition
 measure differences in air pressure, and to calculate the degree to which we amplify or attenuate an audio signal
Term
 what amount doubles/halves the perceived loudness?
Definition
 +/- 10 db
Term
 what is the smallest increment humans can perceive?
Definition
 +/- 3dB
Term
 psychoacoustics are _______sound pressure level (SPL) is ______intensity/power are _________
Definition
 subjectively perceived; objectively measured; theoretically calculated
Term
 what does the equal loudness contour attempt to do?
Definition
 represent the variation in perceived loudness across the frequency spectrum
Term
 what is are two examples of the equal loudness contour?
Definition
 robinson-dadson curves and ISO 226:2003
Term
 what is a wavelength?
Definition
 the point between successive crests of a periodic wave
Term
 what decibel level are humans most sensitive at?
Definition
 2-4K
Term
 what is a phon?
Definition
 unit of loudness level for pure tones
Term
 the number of phons of a sound equals what?
Definition
 the dB SPL of a sound at a frequency of 1kHz that sounds just as loud
Term
 what is the threshold?
Definition
 the point at which a sound becomes inaudible
Term
 what is a transducer?
Definition
 a device that converts variations in a physical quantity, such as pressure or brightness, into an electrical signal, or vice versa
Term
 how does polarity play out in audio signals?
Definition
 towards the positive is typically the compression, and towards the negative is typically the rarefaction
Term
 describe unbalanced cables.
Definition
 transmits an audio signal through two lines: the signal ("hot") and the ground. the receiving device interprets the signal by comparing the hot and ground signals, and any noise or interference picked up along the length of the cable is then included as part of the signal. avoided over 20ft, common connections are TS and RCA
Term
 describe balanced cables.
Definition
 carries the signal via three lines: normal polarity ("hot"), reversed polarity ("cold"), and ground. the receiving device flips the reversed polarity signal which cancels out most noise acquired along the length of the cable. results in a more accurate representation of the source with less noise. common cables are TRS and XLR.
Term
 what is a frequency response?
Definition
 quantitative measure of the output spectrum of a system or device in response to a stimulus*
Term
 what is frequency response plotting relevant for?
Definition
 inputs, amplifiers, effects/processors and outputs
Term
 an equal loudness contour is like...
Definition
 a frequency response plot for human ears
Term
 what is flat frequency response?
Definition
 accurately reflects the sound/signal received
Term
 what is dynamic range?
Definition
 describes the difference between the loudest and quietest portions of an audio signal. can refer to a particular recording or the potential of a particular device
Term
 what are the two instruments that show metering signal levels?
Definition
 the VU and peak meter
Term
 describe the VU.
Definition
 described RMS voltage (root mean square). slightly delayed, but displays "average loudness." slow response and release times (300 ms)
Term
 describe peak meter.
Definition
 displays peaks (transients). fast response, release of actual peaks can be delayed (typically a controllable parameter)
Supporting users have an ad free experience!