# Shared Flashcard Set

## Details

CLI Midterm
Critical Listening for Audio Engineers
98
Audiology
05/11/2010

Term
 Periodic Motion
Definition
 repetitive motion at equal time intervals
Term
 Simple Harmonic Motion
Definition
 periodic motion about a point of equilibrium
Term
 Simple Harmonic Oscillator
Definition
 any object with periodic vibration or motion
Term
 Period
Definition
 time to complete one full cycle of a wave
Term
 Frequency
Definition
 number of complete wave cycles per second (Hertz)
Term
 Extent of Motion
Definition
 distance moved from zero point or equilibrium
Term
 Amplitude
Definition
 amount of displacement from zero point (level or voltage)
Term
 Wavelength
Definition
 length of one complete cycle of a wave
Term
 Equilibrium
Definition
 resting state; zero state
Term
 Velocity
Definition
 magnitude and direction of displacement
Term
 Damping
Definition
 decrease in amplitude from internal and external resistive forces (linear restorative force)
Term
 Elasticity
Definition
 property of mass or a system to return to its original state after being stretched or compressed; restoring force
Term
 Inertia
Definition
 property of mass to stay in motion or at rest until acted upon by external forces (Newtonʼs First Law of Motion)
Term
 Sine Wave
Definition
 fundamental form of all complex waveforms; pure tone with all energy concentrated at one frequency (only one harmonic, the fundamental)
Term
 Wave Properties:
Definition
 Period ! Frequency ! Wavelength ! Amplitude ! Velocity
Term
 Speed
Definition
 how quickly energy can be transferred through the molecular content of a medium (1130 ft./sec. or 344 m/sec at standard atmospheric pressure and 20o C) {Sound travels approximately 1.13 feet per millisecond}
Term
 Wave Propagation
Definition
 pressure wave movement through a medium from an energetic force or disturbance
Term
 Pressure Wave
Definition
 mechanical wave motion consisting of compressions and rarefactions
Term
 Particle Displacement
Definition
 movement of particles in a medium from a state of equilibrium caused by pressure wave energy
Term
 Harmonics
Definition
 frequencies that have a mathematical relationship to a fundamental tone (naturally resonating frequencies)
Term
 Harmonic Series
Definition
 frequencies that are whole number multiples above a fundamental frequency (musically pleasing)
Term
 Octaves
Definition
 doubling or halving a frequency
Term
 Overtones
Definition
 any harmonic without regard to a fundamental or mathematic formula
Term
 Equal Tempered Scale
Definition
 12 tone chromatic harmonic series used in Western music
Term
 Fourier Analysis
Definition
 allows the analysis of frequency, harmonic content, amplitude and phase of complex waveforms; transfer of a form or function into its fundamental components; transfer from the time domain to the frequency domain
Term
 Timbre
Definition
 quality of sound dependent on harmonic content
Term
Definition
 attack, decay, sustain and release; sound envelope that also determines sound quality
Term
 Noise
Definition
 random particle displacement without periodic motion
Term
 Real-Time-Analysis
Definition
 measurement of overall frequency response of a source, system or environment
Term
 Distortion (Non-Linearity)
Definition
 any change to a signal from an input stage to an output stage through an environment, system or device
Term
 Harmonic Distortion
Definition
 any change in amplitude of harmonic content
Term
 Peak Distortion
Definition
 any amplitude changes greater than maximum level
Term
 Clipping
Definition
 any distortion of a waveform usually resulting in a square wave at the extreme
Term
 Phase Distortion
Definition
 any alteration of the phase relationship of audio signals
Term
Definition
 the ability of one signal to cover another
Term
 Superposition
Definition
 the combining of frequency, amplitude and phase of individual waves traversing the same medium at the same time
Term
 Vector Quantity
Definition
 any physical quantity that has both magnitude and direction (velocity, displacement, acceleration)
Term
 Scalar Quantity
Definition
 any physical quantity that possesses magnitude only (speed, distance, temperature)
Term
 Interference
Definition
 distortion that occurs when multiple waves meet or overlap within the same medium
Term
 Constructive Interference
Definition
 positive reinforcement when waves interact (amplitude increase)
Term
 Destructive Interference
Definition
 negative reinforcement when waves interact (phase cancellation)
Term
 Beat Frequencies
Definition
 periodic changes in amplitude when two signals are close in frequency
Term
 Standing Waves
Definition
 wave pattern representing the effect of interference of waves in a medium; not a “true” wave
Term
 Nodes
Definition
 area of minimum displacement in a standing wave
Term
 Antinodes
Definition
 area of maximum displacement in a standing wave
Term
 Resonance
Definition
 natural vibrational frequency of an object or environment; frequency that occurs at an antinode
Term
 Reflections
Definition
 waves from a direct sound that encounter a boundary
Term
 Incident Wave
Definition
 wave from a direct sound
Term
 Angle of Incidence
Definition
 angle of reflection; equal to the angle of the incident wave
Term
 Sound Field
Definition
 any area containing sound waves
Term
 Ideal Sound Field
Definition
 sound field devoid of boundaries
Term
 Near Field
Definition
 immediate area surrounding direct sound
Term
 Far Field
Definition
 area where direct sound and reflections interact
Term
 Free Field
Definition
 area of a sound field where inverse square law still applies
Term
 Reverberant Field
Definition
 area of sound field where reflections tend to have a greater amplitude than the direct sound; loss of intelligibility
Term
 Inverse Square Law
Definition
 for every doubling of distance from a source there is a decrease of -6.02 dB
Term
 Refraction
Definition
 change in speed of sound when encountering mediums of differing densities
Term
 Diffraction
Definition
 change in direction of sound when encountering boundaries
Term
 Haas Effect
Definition
 perceived localization of sound when direct sound and short reflections are combined in the ear (delay time of reflections within 1 mSec-30 mSec); also known as the Precedence effect
Term
 Comb Filter
Definition
 reinforcement and cancellation of interfering waves when arrival time of reflections are very short (1 mSec to 30 mSec); series of harmonically related peaks and nulls across full audio spectrum
Term
 Outer Ear:Pinna
Definition
 collects and funnels sound to the auditory canal; imprints localization " data
Term
 Outer Ear:Concha
Definition
 small opening of auditory canal
Term
 Outer Ear:Auditory Canal (Ear Canal)
Definition
 closed duct (or pipe) terminated by the tympanic membrane; generates resonant frequencies
Term
 Outer Ear:Tympanic Membrane (Ear Drum)
Definition
 small, semi-transparent, oval-shaped membrane that responds to and transmits sound pressure
Term
 Middle Ear:(Tympanic Cavity)
Definition
 air-filled cavity that contains the smallest bones and muscles of the human body
Term
 Middle Ear:Tympanic Membrane
Definition
 ear drum
Term
 Middle Ear:Ossicles
Definition
 malleus, incus and stapes; the small bone chain of the middle ear
Term
 Middle Ear:Malleus (Hammer)
Definition
 connected to the ear drum the malleus transmits the vibrational content it receives from the ear drum to the incus through mechanical action
Term
 Middle Ear:Incus (Anvil)
Definition
 once set into motion by the malleus the incus transmits vibrational energy to the stapes
Term
 Middle Ear:Stapes (Stirrup)
Definition
 the movement of the stapes against the oval window of the inner ear transfers acoustic energy from air to fluid
Term
 Middle Ear:Tensor Tympani
Definition
 small muscle and tendon attached to the malleus that protects the auditory system from excessive sound energy; restricts movement of ear drum by contracting (form of natural compression)
Term
 Middle Ear:Stapedius
Definition
 small muscle and tendon attached to the stapes that moves the stapes " away from the oval window when contracted; protection from loud source signals
Term
 Middle Ear:Eustachian Tube
Definition
 small tube connected to the the throat that maintains equal pressure on both sides of the tympanic membrane; drains middle ear when infections are present
Term
 Inner Ear:Oval Windows
Definition
 small membrane of the cochlea; receives mechanical energy from the stapes and transmits it as pressure waves to the fluid inside the cochlea
Term
 Inner Ear:Cochlea
Definition
 ”sound analyzing organ”; small, coiled, shell shaped organ that analyzes all sound entering the auditory canal
Term
 Inner Ear:Semi-circular Canals
Definition
 three fluid-filled canals responsible for our sense of balance and equilibrium on various axes; detect angular motion on three axes
Term
 Inner Ear:Basilar Membrane
Definition
 membrane separating two fluid-filled tubes along the length of the cochlea; serves as a base for auditory sensory cells; responds to pressure waves in cochlear fluid
Term
 Inner Ear:Organ of Corti
Definition
 central organ of the cochlea containing the hair cells
Term
 Inner Ear:Tectorial Membrane
Definition
 gelatinous membrane in which the stereocilia are embedded; movement of basilar membrane causes shearing of stereocilia under the tectorial membrane
Term
 Inner Ear:Inner Hair Cells
Definition
 receives mechanical vibrations from outer hair cells, converts mechanical energy into neural impulses
Term
 Inner Ear:Outer Hair Cells
Definition
 referred to as the cochlear amplifier, provides sharper tuning of audio signals; increases auditory sensitivity; also capable of not only receiving signals but can transmit signals from within the brain
Term
 Inner Ear:Stereocilia
Definition
 bundles tiny sense organelles that sit atop hair cells; respond to specific frequencies
Term
 Inner Ear:Endolymph
Definition
 high K concentration, similar to intracellular fluids, low Na content; " supposedly causes metabolic actions within the hair cells
Term
 Inner Ear:Perilymph
Definition
 high Na concentration, similar to spinal fluid, low K content; supposedly causes metabolic actions within the hair cells
Term
 Inner Ear:Round Windows
Definition
 small membrane of the cochlea that responds to the pressure changes transmitted through the cochlear fluid from the oval window (compression and rarefaction); acts as a pressure valve
Term
 Threshold of Hearing
Definition
 level of discernible difference in human hearing; 20 μPa (20 x 10-6 referenced at 0 dB
Term
 Threshold of Feeling
Definition
 level of noticeable discomfort or pain 200,000,000 x 10-6 Pascals); referenced as 120 dB
Term
 Range of Hearing
Definition
 sonic range of human auditory system (20 Hz-20 KHz)
Term
 Equal Loudness Contours
Definition
 displays the changes in sensitivity of human hearing to frequencies across the audible range
Term
 Area of Audibility
Definition
 audible ranges of speech, music and overall sound Critical Bands-areas along the basilar membrane that vibrate in response to certain frequencies; frequency ranges around a center frequency that allow us to discern individual frequencies in complex waveforms
Term
 Fundamental Tracking
Definition
 the ability of the ear to detect a missing fundamental in a mathematical related harmonic series
Term
 Equation:Period
Definition
 1/f
Term
 Equation:Frequency
Definition
 1/T
Term
 Equation:Wavelength
Definition
 1130/f (feet/second) or 334/f (meters/second)
Term
 Equation:Inverse Square Law
Definition
 20 log (D2/D1)
Term
 Equation:Comb Filter (first null)
Definition
 f=1/(2T)
Term
 Equation:Comb Filter (first peak)
Definition
 f=1/T (also equals distance between peaks)
Term
 Equation:Chromatic Half Step
Definition
 1.05946 * f₁
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