# Shared Flashcard Set

## Details

Introduction to Hearing Science
Stiritz
388
Audiology
01/15/2013

Term
 What is Sound
Definition
 a vibration a medium must be capable of being set into vibration must have mass & elasticity to do so
Term
 Mass (m)
Definition
 amount of matter present applies to gases, liquids, & solids related to density has inertia - opposes change in motion scalar
Term
 Force (F)
Definition
 = ma measured in N or dynes push or pull on an object applied to overcome inertia (mass) a vector
Term
 Density (ρ)
Definition
 mass per unit volume effects how sound is transmitted ↑ ρ = ↑ speed of sound
Term
 Elasticity (E)
Definition
 deform in shape, size, or length enables recovery from distortion measured in stiffness or its reciprocal, compliance seen when a force is applied to an object
Term
 Displacement
Definition
 movement from an original position force > friction vector length & direction
Term
 Equilibrium (FNET)
Definition
 no displacement no movement net force zero
Term
 Friction
Definition
 always opposes motion occurs when surfaces are in contact with one another = resistance < force = displacement
Term
 Vibratory Motion
Definition
 form of motion used in acoustics AKA oscillation back-and-forth type of movement through equilibrium Simple Harmonic Motion (SHM) is the simplest type
Term
 Simple Harmonic Motion
Definition
 force is applied to an object displacement occurs amount of displacement is a result of a combination of force applied, mass, elasticity of medium, friction, etc. results in oscillation (vibratory motion) represented mathematically by SINE AKA sinusoidal motion or sine wave
Term
 Transverse Wave
Definition
 one type of oscillating movement direction of vibration is perpendicular to the direction of the force that propagated the vibration e.g. guitar strings, pebble dropped in water, moving a rope up & down causes a wave to go outward
Term
 Longitudinal Wave
Definition
 a type of oscillating wave oscillation is parallel to the force  e.g. a spring, sound waves forms compressions & rarefactions
Term
 Sound Waves
Definition
 are longitudinal waves particles oscillate about their equilibrium & cause a force on neighboring particles which puts them in motion
Term
 Waveform Representation
Definition
 [image]
Term
 Dimensions of a Sine Wave
Definition
 Frequency Period Wavelength Phase Amplitude are all independent of each other
Term
 Frequency
Definition
 how fast the oscillation is cycles per second Hertz (Hz) reciprocal of period = 1/p the eardrum vibrates at the same frequency of sound
Term
 Period (p)
Definition
 time required to complete one cycle seconds reciprocal of frequency = 1/freq.
Term
 Equation for Period
Definition
 p = 1 / f   (s)
Term
 Equation for Frequency
Definition
 f = 1 / p   (Hz or cps)
Term
 Wavelength (λ)
Definition
 the distance between successive points on a sine wave inversely related to frequency ↑ freq. = ↓ λ
Term
 Speed of Sound
Definition
 is affected by humidity, elasticity, density, temperature 340 m/s (through air; 0 degrees C; at sea level) = √(E/ρ) proportional to elasticity inversely proportional to density not affected by frequency
Term
 Equation for Speed of Sound
Definition
 s = √E/ρ   (m/s)
Term
 Equation for Wavelength
Definition
 λ = s / f   (mm)   s = speed of sound (340 m/s)
Term
 Natural Frequency (fnat)
Definition
 AKA resonant frequency the frequency with which a system oscillates freely dependent on a system's mass & elasticity (stiffness)
Term
 Equation for Natural Frequency
Definition
 fnat = √ (s / m)   s = stiffness (elasticity) m = mass
Term
 Phase
Definition
 quantify a point on the graph 0°, 90°, 180°, 270°, 360° what direction one cycle = 360°
Term
 Uniform Circular Motion
Definition
 90° & 270° = xMAX 0°, 180°, & 360° = equilibrium 360° = one cycle
Term
 Starting Phase
Definition
 the ear is the most sensitive to the angle the moment rotation begins[image]
Term
 Amplitude (A)
Definition
 = displacement AKA intensity; pressure y-axis
Term
 Instantaneous Amplitude (a)
Definition
 one particular part on the graph
Term
 Maximum/Peak Amplitude (A)
Definition
 only one side of graph (either positive or negative) (P-P)/2 [image]
Term
 Peak-to-Peak Amplitude (P-P)
Definition
 displacement from one side to the other = 2(A) [image]
Term
 Root-Mean-Square Amplitude (A rms)
Definition
 best measurement for complex sounds an average of amplitude = .707 amplitude peak = .3535 peak to peak amplitude = standard deviation
Term
 Effects of Friction on Vibratory Motion
Definition
 limits particle displacement causes amplitude of vibration to dampen over time A - loss-less system B - low-dampened system C - high-dampened system  [image]
Term
 Systems of Measure
Definition
 Metric: MKS & cgs US: fps [image]
Term
 Acceleration
Definition
 = F/m change in velocity positive or negative (deceleration) e.g. a car going 65 mph (velocity) speeds up to 75 mph = 10 mph (acceleration)
Term
 Velocity
Definition
 vector (m/s; mph) your speed a change = acceleration/deceleration
Term
 Conversion of Newtons to Dynes
Definition
 1 N = 100,000 dynes
Term
 Pressure
Definition
 force applied to a surface area measured in dynes/cm2 or Pa (N/m2) = √(intensity) vector
Term
 Conversion of Pascals to dynes/cm2
Definition
 1 N/m2 = 10 dynes/cm2
Term
 Relationship between Speed of Sound & Density
Definition
 inversely proportional   Density ↑ Speed of Sound ↓
Term
 Relationship between Speed of Sound & Elasticity
Definition
 directly proportional   Speed of Sound ↑ Elasticity ↑
Term
 Relationship between Density & Mass
Definition
 directly proportional   m ↑ = ρ ↑
Term
 Relationship between Period & Frequency
Definition
 inversely proportional   P ↑ = f ↓
Term
 Relationship between Wavelength & Frequency
Definition
 inversely proportional   λ ↑ = f ↓
Term
 A rms = A%
Definition
 70.7%
Term
 A rms = P-P%
Definition
 35.35%
Term
 Equation for Acceleration
Definition
 a = F / m   F = force m = mass
Term
 Equation for Force
Definition
 F = ma    (dynes or N)
Term
 Relationship between Acceleration & Mass
Definition
 inversely proportional   m ↑ = a ↓
Term
 Relationship between Acceleration & Force
Definition
 directly proportional   F ↑ = a ↑
Term
 Dynamic Range of the Ear in Pressure
Definition
 the range between the least amount of pressure detected & the pain threshold of the ear .0002 dynes/cm2 — 200,000,000 dynes/cm2
Term
 Power
Definition
 is the capacity to exert energy or force is measured in horsepower or watts   same relationship with intensity that force has with pressure
Term
 Intensity
Definition
 power distributed over a surface area measured in watts/cm2 = pressure2
Term
 Dynamic Range of the Ear in Intensity
Definition
 the range that the human ear can detect 1 x 10-16 watts/cm2 — 1 x 10-2 watts/cm2
Term
 Natural Logs
Definition
 simply exponents exponent = log log 106 = 6 (power/intensity)
Term
 Common Logs
Definition
 need calculator or log table e.g. log 4 = .6 (force & pressure)
Term
 Log Rules for Multiplication
Definition
 ADD log (A x B) = log A + log B
Term
 Log Rules for Division
Definition
 SUBTRACT log (A / B) = log A - log B
Term
 Log Rules for Exponents
Definition
 MULTIPLY log AB = B log A
Term
 Logarithmic Scale
Definition
 = a ratio scale one unit on a scale is so many times greater or less than another        (/10)   (/10)    (/10)     (/10)    (x10)    (x10)    (x10)   (x10) <------l-------l-------l-------l-------l-------l-------l------->         -1000  -100    -10       0       10      100     1000
Term
 Bel
Definition
 artificial ratio between whatever sound is being measured & the softest sound a human ear can detect log Ix / Ir use log to reduce the amount of 0s
Term
 Convert Bels to Decibels
Definition
 a decibel is 1/10 of a bel dB / 10 = 1 bel 1 bel = 10 decibels
Term
 Calculating dB IL
Definition
 10 log (Ix / Ir)
Term
 Increase in dB IL when Sound Source is Doubled
Definition
 10 log 2 / 1 = 10 (log 2 - log 1) = 10 (.3 - 0) = 3 dB IL
Term
 Relationship between Intensity & Pressure
Definition
 I = P2
Term
 Increase in dB spl when Pressure is Doubled
Definition
 20 log (2/1) 20 (log 2 - log 1) 20 (.3 - 0) = 6 dB spl
Term
 20 dB IL, Calculate Ix
Definition
 20 = 10 log (Ix / 10-16 watts/cm2) 20/10 = log Ix - log 10-16 2 = log Ix + 16 -14 = log Ix antilog = 10-14 watts/cm2
Term
 2 Ways to Measure Sound
Definition
 Intensity (dB IL) Pressure (dB spl)
Term
 Calculate dB spl
Definition
 20 log (px / pr) pr = .0002 dynes/cm2
Term
 Physicist's Zero
Definition
 the smallest variation detected by a young, normal-hearing individual .0002 dynes/cm2 and 10-16 watts/cm2
Term
 Correlated Sound Source
Definition
 the signal is identical in every aspect (frequency, amplitude, phase) from each sound source unrealistic
Term
 Uncorrelated Sound Source
Definition
 the signal is not identical frequency, amplitude, phase are independent real world
Term
 Adding Uncorrelated Sound Sources with Equal dBs
Definition
 dBi + 10 log N = total dB (IL or spl)   dBi = dB of source N = number of sources
Term
 Adding Uncorrelated Sound Sources with Unequal dBs
Definition
 Convert dBs (IL or spl) to watts/cm2 A dB = 10 log x / 10-16 watts/cm2 B dB = 10 log x / 10-16 watts/cm2 Add watts/cm2 must have equal exponents Convert back to dBs dB = 10 log _____ / 10-16 watts/cm2
Term
 Sound Pressure Reference (pr)
Definition
 .0002 dynes/cm2 or .00002 dynes/m2
Term
 Calculating dB spl
Definition
 20 log (px /pr)
Term
 Intensity Reference (Ir)
Definition
 1 x 10-16 watts/cm2 or 1 x 10-12 watts/m2
Term
 Complex Stimuli
Definition
 any sound that is NOT sinusoidal composed of 2 or more sine waves that can differ in amplitude, frequency, & phase graphed on a spectrum line graph x-axis is frequency y-axis is usually amplitude
Term
 Summation of Sine Waves
Definition
 make a complex wave add instantaneous amplitudes together  [image]
Term
 Fourier Series
Definition
 a complex wave that consists of a series of simple sinusoids that can differ in amplitude, frequency, & phase can be derived from Fourier analysis Fourier's Theorem
Term
 Fourier Analysis
Definition
 a process of decomposing or analyzing a complex waveform to determine its individual sinusoidal components this is what the cochlea does Fourier's Theorem
Term
 Periodic Wave
Definition
 a wave that repeats itself over time AKA periodic time function can be either sinusoidal or complex [image]
Term
 Components of a Complex, Periodic Wave
Definition
 must satisfy a harmonic relation sinusoidal components cannot be selected at random
Term
 Fundamental Frequency
Definition
 the lowest common denominator f0= 1/t represented by the first harmonic on a spectrum
Term
 Harmonics
Definition
 the frequencies of all of the sinusoids must be integer (whole number) multiples of the lowest frequency component (f0) 1/t, 2/t, 3/t, 4/t, etc. added together you get a complex sound e.g. if f0=100 Hz, then... f1= 100 Hz, f2=200 Hz, f3=300 Hz, f4=400 Hz
Term
 The Octave
Definition
 a doubling or halving of frequency a frequency ratio of 2:1 or 1:2 (not a frequency difference) 3000 Hz is 2 octaves above 1000 Hz
Term
 Aperiodic Complex Waves
Definition
 combination of sounds not harmonically related continuous (can be sustained) noise (unwanted sounds)
Term
 Acoustical Noise
Definition
 instantaneous amplitude varies over time 3 types: Gaussian noise Sawtooth noise Pink noise
Term
 Gaussian Noise
Definition
 a type of white noise (static) with random amplitudes amplitudes vary according to a normal curve contains all frequencies and random phases
Term
 Sawtooth Noise
Definition
 high frequencies emphasis random amplitude & phases
Term
 Pink Noise
Definition
 low frequencies emphasis random amplitude & phase
Term
 Signal-Noise Ratio
Definition
 way of describing the level of noise in relation to the level of signal signal : noise e.g. 60 dB/ 50 dB = +10 dB (signal is 10 dB more intense than the noise) e.g. 50 dB/ 70 dB = -20 dB
Term
 Transients
Definition
 brief acoustic events short durations (e.g. clicks) the shorter, the broader the frequency spectrum e.g. t = 1 ms -> 1/t = 1000Hz ->1000 different frequencies
Term
 The Principle of Resonance
Definition
 periodic force is applied to an elastic system system is forced to vibrate at frequency of applied force (not at fnat) the closer the frequency of the applied force to the    fnat of the system, the greater the amplitude of vibration
Term
 Resonators
Definition
 a filter an object vibrates the greatest at its natural frequency and lessen in magnitude as it moves away
Term
 Filters
Definition
 a type of resonator is a frequency-specific elastic system allows the frequency of the vibrating object to be modified
Term
 5 Parameters of a Filter
Definition
 Center Frequency Upper Cut-off Lower Cut-off Bandwidth Rejection Rate/Attenuation Rate/Roll-Off/Slope
Term
 Center Frequency
Definition
 fc AKA natural frequency  parameter of a filter
Term
 Upper Cut-Off Parameter of a Filter
Definition
 fu  frequency above fc at which the power is 3-dB-down [image] parameter of a filter
Term
 Lower Cut-Off Parameter of a Filter
Definition
 fl  frequency below fc at which the power is 3-dB-down  [image]
Term
 Bandwidth Parameter of a Filter
Definition
 Δf or BW = fu - fl defines the bandpass of the system the range of frequencies passed by the filter quantifies how narrowly or broadly tuned the filter is parameter of a filter
Term
 Attenuation Rate Parameter of a Filter
Definition
 the rate at which energy for frequencies is rejected the slope of the filter curve dB/octave AKA rejection rate, roll-off, slope parameter of a filter
Term
 4 Types of Filters
Definition
 Low-Pass High-Pass Band-Pass Band-Reject
Term
 Low-Pass Filter
Definition
 attenuates energy above fu passes energy below some fu 2 parameters: fu attenuation rate Δf = fu [image]  a type of filter
Term
 High-Pass Filter
Definition
 attenuates energy below fL passes energy above some fL [image] type of filter
Term
 Band-Pass Filter
Definition
 is a combination of a low-pass & high-pass filter connected in series signal → LP → HP  (or vice versa) [image]  type of filter
Term
 Band-Reject Filter
Definition
 rejects energy between some fL & fU is a combination of a low- & high-pass filter connected in parallel signal → LP & HP [image]  type of filter
Term
 Distortion
Definition
 frequencies or amplitudes are in the output that were not there in the input all electrical systems produce it different types: frequency amplitude  [image]
Term
 Frequency Distortion
Definition
 when filtering has occurred related to harmonics summation tones (e.g. f1+f2, 2f1+f2, f1+2f2) difference tones (e.g. f1-f2, f1-2f2, f1-3f2) magnitude expressed in a percentage proportion of total energy that is undesired energy x 100%
Term
 Sound Transmission
Definition
 medium needs elasticity & mass to conduct sound sound must be propogated or have a source sound source transfers energy to the air, allowing for the energy to actually move through the air
Term
 Density of Air
Definition
 400 billion (4 x 1020) molecules per cubic inch
Term
 Sound Wave Travels
Definition
 air molecules pass energy from one molecule to the next each molecule only moves an infinitesimal amount from its equilibrium creates a force on the molecule next to it sound waves constantly encounter barriers in their travels
Term
 Impedance
Definition
 is the opposition that energy encounters when it is transferred from its source to a system (load) e.g. larynx (source) → air (medium) → wall (barrier) a vector reactance—mass & elasticity resistance—friction
Term
 When Impedance Occurs...
Definition
 1 or a combination of 4 things happen... transmission reflection absorption diffraction energy is not lost or created; only changes form
Term
 Transmission
Definition
 can happen when impedance occurs (1 of 4) amount of energy that successfully travels from the source to the load the impedance of the source must be similar to the impedance of the load opposite of reflection
Term
 Equation for Transmission
Definition
 H = 4 Za Zb / (Zb + Za)2 H = proportion of energy transmitted Za = impedance of medium (source) Zb = impedance of medium (load)
Term
 Reflection
Definition
 can happen when impedance occurs (1 of 4) the amount of energy that is not transferred from the source to the load opposite of transmission 2 waves: incident reflective
Term
 Equation for Reflection
Definition
 H = 4 Za Zb / (Zb - Za)2 H = proportion of energy transmitted Za = impedance of medium (source) Zb = impedance of medium (load)
Term
 Incident Wave
Definition
 the original wave a wave of reflection (1 of 2)
Term
 Reflective Wave
Definition
 the energy that bounces back is always at the same angle as the incident wave perpendicular travel at the same speed as the incident wave can interact with the incident wave in a medium standing waves destructive interference constructive interference
Term
 Echo
Definition
 time delay between the reflected waves & the original wave can sometimes be detected by the ear reflected sound referred to as reverberation if not detected by the ear
Term
 Reverberation
Definition
 time it takes, in seconds, for a sound to decrease 60 dB .001 of its original amplitude (damping) longer time—highly reflective surfaces; larger rooms shorter time—absorptive surfaces none—anechoic chambers
Term
 Optimal Reverberation Time for Speech
Definition
 0.8 - 1.1 seconds ↑ reverberation time = ↓ speech intelligibility
Term
 Standing Waves
Definition
 the 2 waves are identical except they are out-of-phase the waves cancel creating a dead spot in the environment created by complete destructive interfence appears as if the vibrations are standing still an interaction between the reflected wave and the original wave (1 of 3)
Term
 Destructive Interference
Definition
 the amplitude of the interacting wave is less than the original complete interference creates standing waves an interaction between the reflected wave and the original wave (1 of 3)
Term
 Constructive Interference
Definition
 the amplitude of the interaction is increased an interaction between the reflected wave and the original wave (1 of 3)
Term
 Absorption
Definition
 can happen when impedance occurs (1 of 4) minimizes transmission & reduces reflections energy is absorbed & dissipated in the form of heat inversely proportional to the amount of reflection
Term
 Diffraction
Definition
 can happen when impedance occurs (1 of 4) sound goes around an object dependent of the wavelength and the size of the object object < λ → sound passes object > λ → sound stops object = λ → sound shadow can either be wanted or unwanted does not bend like during refraction
Term
 Refracted Waves
Definition
 a special type of reflected wave encountering something in its path causes it to bend travels at a slower speed than the incident wave e.g. traveling through an open door
Term
Definition
 occurs during diffraction when the size of an object equals the wavelength equals the size of the wavelength AKA dead spot
Term
 Doppler Effect
Definition
 perceptual change in the pitch of a sound caused by the movement of a sound source source moving towards listener waves are compressed - ↓ λ raises the pitch & the frequency  source moves away from listener waves are stretched - ↑ λ pitch is perceived as lower because the frequency decreases e.g. train passing by a stationary listener
Term
 Calculating Doppler Effect
Definition
 away from listener: f' = f [s / (s + ss)] towards listener: f' = f [s / (s - ss)] f' = altered frequency f = frequency s = speed of sound (340 m/s) ss = speed of moving sound source
Term
 Inverse Square Law
Definition
 when sound is propagated in a free, unbounded medium (no obstacles), intensity decreases in a lawful way energy twice as far from the source is spread over four times the area, hence one-fourth the intensity
Term
 Equation for Inverse Square Law
Definition
 1 / (di / dr)2 = -20 log (di / dr) intensity is inversely proportional to the square of the distance from the source intensity decreases by 6 dB everytime the distance from the sound source is doubled (-20 log 2/1)
Term
 Soundfields
Definition
 environment in which sound exists soundproof or anechoic free field near field far field
Term
 Near Field
Definition
 within 1 meter of source no inverse square law no decrease in amplitude acts as a free field no standing waves
Term
 Far Field
Definition
 further than 1 meter from source diffraction, absorption, & reflection possible inverse square law applies
Term
 Line Spectrum
Definition
 the complex periodic waves can be represented by a set of lines energy is present only at frequencies represented by the vertical lines [image]
Term
 Continuous Spectrum
Definition
 representation of an aperiodic waveform of noise energy is present at all frequencies between certain lower and upper frequency limits graph is a straight horizontal line
Term
 Peripheral Auditory System
Definition
 outer ear middle ear inner ear VIII nerve
Term
 Central Auditory System
Definition
 brain stem cerebrum corpus callosum
Term
 Temporal Bone
Definition
 contains the organs of hearing and balance 4 parts: squamous portion mastoid process tympanic portion petrous portion
Term
 Squamous Portion of the Temporal Bone
Definition
 lies in front & above the ear canal fan-like portion 1 of 4 parts of temporal bone
Term
 Mastoid Process
Definition
 behind ear very thick filled with holes & air 1 of 4 parts of temporal bone
Term
 Tympanic Portion of Temporal Bone
Definition
 forms bottom & sides of ear canal 1 of 4 parts of temporal bone
Term
 Petrous Portion of Temporal Bone
Definition
 medial portion projecting inward contains organs of hearing & balance 1 of 4 parts of temporal bone
Term
 [image]
Definition
 A. temporal bone                 B. malleus                           C. incus                               D. stapes                             E. semi-circular canals         F. vestibular nerve              G. facial nerve                     H. internal auditory meatus I. cochlear nerve J. cochlea K. eustachian tube L. tympanic cavity M. tympanic portion N. tympanic membrane O. internal auditory meatus P. pinna
Term
 [image]
Definition
 A. squamous portion B. zygomatic arch C. mastoid portion D. external auditory meatus E. tympanic portion F. ramus of the mandible
Term
 Outer Ear Anatomy
Definition
 most lateral & inferior portion of auditory pathway part of the peripheral auditory system includes the pinna & the external auditory canal
Term
 Pinna
Definition
 AKA auricle made of cartilage functions: a resonator for frequencies around 5 kHz small muscles attach to cartilage (vestigial) several small muscles within (vestigial)
Term
 [image]
Definition
 A. helix                         B. scaphoid fossa           C. anti-helix                  D. cymba concha           E. cavum concha           F. helix                          G. anti-tragus H. ear lobe I. triangular fossa J. crus of helix K. tragus L. intertragal incisure
Term
 External Auditory Meatus (EAM)
Definition
 opening into external auditory canal
Term
 External Auditory Canal (EAC)
Definition
 extends medially & posterior for about 2.5 cm in adults begins & ends with a slope downward allowing for drainage fungus may form at far end s-shaped lined with skin
Term
 Outer 1/3 of EAC
Definition
 cartilage continuous from pinna ceruminous glands (sweat) & sebacious glands (sebum) together form cerumen slight antibacterial & antifungal characteristics contains cilia that push out debris & cerumen
Term
 Inner 2/3 of EAC
Definition
 passes through tympanic portion no glands or hair begins at osseocartilaginous junction ends at tympanic membrane
Term
 Osseocartilaginous Junction
Definition
 point where the outer 1/3 & inner 2/3 of EAC meet lies directly above the temporomandibular joint site of secondary pain for TMJ syndrome can get otalgia (pain) & edema (swelling)
Term
 Outer Ear Physiology
Definition
 cosmetic nature protects TM cerumen helps collect foreign objects cerumen moves itself out of EAC amplification localization
Term
 Outer Ears Role in Amplification
Definition
 acts as a resonator pinna: increase of 3-4 dB at 3-4 kHz concha: increase of 10-15 dB at 1.5-7 kHz EAC: increase of 10-15 dB at 2.5 kHz
Term
 Outer Ear's Role in Localization
Definition
 filtering properties cause a boost in high frequencies which help locate sounds, particularly from above & below speech perception of consonants, particularly in background noise color the spectrum of sounds an individual gets use to the sound of his own pinna & EAC
Term
 Tympanic Membrane
Definition
 boundary of outer & middle ear concave structure made of 3 membranes (outer, middle, inner) consistes of 2 areas (pars flaccida & pars tensa)
Term
 Outer Layer of the Tympanic Membrane
Definition
 same skin as in the canal
Term
 Middle Layer of the Tympanic Membrane
Definition
 elastic conductive layer; fibrous 2 sets of fibers: radial linear
Term
 Inner Layer of Tympanic Membrane
Definition
 same mucous cells that line the middle ear cavity
Term
 Pars Flaccida
Definition
 AKA Shrapnell's membrane most superior 1/4 of TM does not contain the fibers that make the TM tight
Term
 Pars Tensa
Definition
 inferior 3/4 of TM very tight or tense due to fibers
Term
 [image]
Definition
 A. pars flaccida B. long process of incus C. manubrium of malleus D. umbo E. pars tensa F. tympanic annulus G. light reflex (cone of light)
Term
 Surface Area of TM
Definition
 85 mm2 of area only 2/3 (55 mm2) vibrates at any given time
Term
 Umbo
Definition
 TMs place of attachment to the manubrium of the malleus at the center
Term
 Tympanic Annulus
Definition
 holds the TM in place at the edges
Term
 Purpose of Tympanic Membrane
Definition
 energy transducer changes acoustic vibrations to mechanical vibrations
Term
 Middle Ear Anatomy
Definition
 air-filled cavity 1/2" high by 1/2" wide by 1/4" deep surrounded by bone inferior: jugular bulb anterior: eustachian tube & carotid artery medial: oval window, promontory, & round window
Term
 Eustachian Tube (ET)
Definition
 AKA auditory tube equalizes pressure between ME & environment opens to nasopharynx lined with cilia normally closed (attenuates voice) opened by tensor veli palatini & levator veli palatini muscles
Term
 Parts of the ME
Definition
 superior: epitympanic recess or attic posterior: parts of chorda tympani & stapedius muscle anterior: eustachian tube medial: oval window, round window, promontory ossicular chain very rigid (vibrate, but doesn't move around) 5 ligaments, , 2 tendons, 2 muscles
Term
 [image]
Definition
 A. tympanic membrane B. tympanic annulus C. malleus D. epitympanic recess E. incus F. stapes G. oval window H. eustachian tube
Term
 [image]
Definition
 A. malleus B. head C. articular facet D. neck E. anterior process F. lateral process G. manubrium
Term
 [image]
Definition
 A. incus B. short process C. anterior facet D. articular facet E. long process F. lenticular process
Term
 [image]
Definition
 A. stapes B. head C. neck D. anterior crus E. obturator foramen F. posterior crus G. footplate
Term
 Ligaments in the ME
Definition
 lateral ligament superior ligament anterior ligament posterior ligament annular ligament
Term
 Lateral Ligament in the ME
Definition
 manubrium of malleus to temporal bone in inferior part of attic
Term
 Superior Ligament in the ME
Definition
Term
 Anterior Ligament in the ME
Definition
 malleus manubrium to anterior portion of temporal bone
Term
 Posterior Ligament in the ME
Definition
 incus to temporal bone
Term
 Annular Ligament in the ME
Definition
 stapes to temporal bone in medial wall holds footplate in OW
Term
 Tendons in the ME
Definition
 tendon of the stapedius muscle tensor tympani
Term
 Tendon of the Stapedius Muscle
Definition
 stapes to stapedius muscle able to measure contraction (stapedius reflex) tendon in middle ear
Term
 Tensor Tympani Tendon
Definition
 tensor tympanic muscle to malleus tendon in middle ear
Term
 Muscles of the ME
Definition
 stapedius muscle tensor tympani
Term
 Stapedius Muscle
Definition
 reduces vibration by twisting innervated by facial nerve (VII) helps protect the cochlea muscle of the middle ear
Term
 Tensor Tympani Muscle
Definition
 impedes the vibration of the malleus & TM innervated by trigeminal nerve (V) helps protect the cochlea muscle of the middle ear
Term
 Chorda Tympani
Definition
 branch of the facial nerve taste info runs from posterior of IE and below the incus
Term
 ME Physiology
Definition
 transducer (TM changes acoustic energy to mechanical) conducts mechanical energy to the IE an impedance matcher (tensor tympani muscle) otherwise 99% of energy would be reflected back would lose 30 dB if energy went from air to fluid makes up for this by area difference, lever action & buckling of eardrum
Term
 Area Difference between TM & Stapes Footplate
Definition
 1 of the 3 ways the ME makes up for the loss of energy 55 mm2 : 3.2 mm2 (area of TM : area of footplate) 24.7 dB increase number changes depending on how much the TM is vibrating takes the energy and concentrates it to a small area e.g. thumbtack
Term
 Lever Action of the Ossicular Chain
Definition
 1 of the 3 ways the ME makes up for the loss of energy the fulcrum of the ossicular chain is closer to the stapes & not in the middle allows for a 1.3 : 1 increase of pressure at the oval window about 2-3 dB increase
Term
 Buckling of the TM
Definition
 1 of the 3 ways the ME makes up for the loss of energy TM doesn't vibrate uniformly across surface more at the curved areas less at the umbo which creates an increase in force at umbo 3-4 dB increase
Term
 Series of Labyrinths
Definition
 a maze of connected tunnels in the IE Osseous Labyrinth: bony section carve bone around organs of hearing & balance contains perilymph Membranous Labyrinth inside bony portion contains endolymph 3 divisions (cochlea, semi-circular canals, vestibule)
Term
 [image]
Definition
 A. endolymphatic sac B. vestibular aqueduct C. endolymphatic duct D. saccule E. utricle F. semi-circular canals G. ductus reuniens H. cochlear aqueduct I. round window J. oval window K. scala vestibuli L. scala media M. scala tympani
Term
 Semi-Circular Canals
Definition
 organ of balance epsilateral 3 canals at right angles to each other superior (anterior), posterior, lateral (horizontal) contain endolymph are sensitive to rotations that lie in the plane of the canal one side is excitatory & the other side is inhibitory superior is paired with posterior lateral is paired with lateral
Term
 Ampulla
Definition
 organ of balance encodes angular acceleration or rotation bulges found where the canals attach to vestibule contain crista ampullaris & cupula
Term
 Crista Ampullaris
Definition
 organ for balance in the ampulla (semi-circular canals) contains ciliated sensory cells embedded in cupula release NT during angular acceleration
Term
 Cupula
Definition
 in the semi-circular canals a gelatinous mass where the cilia from the crista ampullaris is embedded composed of a crystalized lime may harden with age & break off, causing dizziness encodes angular acceleration
Term
 [image]
Definition
 A. ampulla B. cupula C. crista ampullaris D. cilia E. semi-circular canal
Term
 Utriculorsaccular Portion
Definition
 located in vestibule 2 parts: utricle saccule contains endolymph, maculae, & otoliths encodes linear acceleration
Term
 Maculae
Definition
 organ for balance in the utriculosaccular portion contains ciliated sensory cells  covered by otolith release NT during linear acceleration
Term
 Otoliths
Definition
 in the utriculosaccular portion a gelatinous mass covering the maculae made of calcium carbonate crystals movement causes cilia to pull on the maculae, which causes a chemical reaction (graded potential) encodes linear acceleration
Term
 Encoding Balance Information
Definition
 stereocilia on top of the cells move as the fluid moves hair cell changes the mechanical energy to electrochemical energy of a graded potential carried by the vestibular portion of the VIII CN
Term
 Neural Projections
Definition
 go to vestibular nuclei in medulla major connections to the cerebellum feedback from cerebellum back to the brain stem major projections: vestibulocular projections (visual) vestibulospinal projections (motor)
Term
 Superior Vestibular Nuclei
Definition
 output to the medial longitudinal fasiculus then projections are sent to the ipsilateral... oculomotor trochlear abducens spinal accessory allows for the coordination of eye movement & head/neck movement innervated by the CN VIII
Term
 Oculomotor Nuclei
Definition
 III innervates 4 of 6 eye muscles receives projections from superior vestibular nuclei through the MLF
Term
 Trochlear Nuclei
Definition
 IV innervates 1 of 6 eye muscles receives projections from superior vestibular nuclei through the MLF
Term
 Abducens Nuclei
Definition
 VI innervates 1 of 6 eye muscles receives projections from superior vestibular nuclei through the MLF
Term
 Spinal Accessory Nuclei
Definition
 XI head & neck movement function in speech & swallowing receives projections from superior vestibular nuclei through the MLF
Term
 Medial Longitudinal Fasciculus
Definition
 receives info from the superior vestibular nucleus a fiber tract that connects motor nuclei III, IV, VI, & XI runs midline through the medulla, pons, and midbrain
Term
 [image]
Definition
 A. cerebellum B. VIII (balance portion) C. superior D. oculomotor E. trochlear F. abducens G. medial H. inferior I. lateral J. medial longitudinal fasciculus K. spinal accessory
Term
 Medial Vestibular Nuclei
Definition
 output to the cerebellum innervated by the CN VIII
Term
 Inferior Vestibular Nuclei
Definition
 output to the cerebellum innervated by the CN VIII
Term
 [image]
Definition
 A. annular B. lateral C. posterior D. anterior E. superior F. stapedius muscle
Term
 Cerebellar Cortex Input
Definition
 organized horizontally from spinal cord, pons, & vestibular system how many muscles to be stimulated & timing   [image]
Term
 Cerebellar Cortex Output
Definition
 organized vertically (right & left):  [image]
Term
 Anterior Lobe
Definition
 input from spinal cord horizontal division of cerebral cortex
Term
 Posterior Lobe
Definition
 input from pons horizontal division of cerebral cortex
Term
 Flocculonodular Lobe
Definition
 input from vestibular input from lateral, medial, & inferior nuclei horizontal division of the cerebral cortex
Term
 Vermis
Definition
 input from spinal cord, pons, & vestibular output through the fastigial nuclei to the  lateral vestibular nuclei (primarily) reticular formation (some) to spinal cord lies directly on the seam "worm" vertical division of the cerebral cortex
Term
 Fastigial Nuclei
Definition
 input from the vermis output to lateral vestibular nuclei & reticular formation to spinal cord
Term
 Paravermis
Definition
 input from spinal cord, pons, & vestibular output through interposed nuclei to the red nuclei (primarily) ventrolateral nucleus (some) to spinal cord middle area of cerebellum vertical division of cerebral cortex
Term
 Cerebellar Cortex
Definition
 gray matter (lack myelin sheath) outer portion of cerebellum input (horizontally) from spinal cord, pons & vestibular output (vertically) from vermis, paravermis & lateral hemisphere functions: fine movement coordination balance & equillibrium muscle tone
Term
 Vestibular Nuclei
Definition
 in the 4th ventricle (floor of medulla) superior, lateral, medial, & inferior innervated by the balance portion of the VIII CN sends info to cerebellum, MLF, & vestibulospinal tract
Term
 Feedback from Cerebellum to Vestibular System
Definition
 concerning proprioception constantly updated, which allows equilibrium maintenance
Term
 Lateral Vestibular Nuclei
Definition
 input from the vermis through the fastigial nuclei output to spinal cord  & cerebellum  innervated by the CN VIII
Term
 Reticular Formation
Definition
 input from the vermis through the fastigial nuclei  output spinal cord
Term
 Interposed Nuclei
Definition
 input from the paravermis output to red nuclei (primarily) ventrolateral nucleus (some)
Term
 Red Nuclei
Definition
 primary input from the paravermis through the interposed nuclei (motor-efferent) output to the spinal cord input from the lateral hemisphere through the dentate nuclei  output to the motor cortex to the spinal cord
Term
 Ventrolateral Nucleus
Definition
 input from the paravermis through the interposed nuclei (sensory - afferent) output to the spinal cord primary input from the lateral hemisphere through the dentate nuclei output to the motor cortex to spinal cord of the thalamus (sensory relay station)
Term
 Lateral Hemisphere
Definition
 input from spinal cord, pons, & vestibular output through the dentate nuclei to ventrolateral nuclei (primarily) red nucleus (some) to the motor cortex (#4) to spinal cord via corticospinal tract the largest part of the cerebellar cortex vertical division
Term
 Dentate Nuclei
Definition
 input from the lateral hemisphere output to the ventrolateral nuclei (primarily) red nucleus (some) to the motor cortex (#4) to the spinal cord largest of the nuclei
Term
 Motor Cortex
Definition
 input from the lateral hemisphere via the ventrolateral nuclei & the red nucleus output to the spinal cord via the corticospinal tract Brodmann's area #4
Term
 Nystagmus
Definition
 movement of the eye in the opposite direction of the movement of the head the eye's attempt to stabilize an image and make sense of what you're seeing so that it isn't just a blur can be measured by an ENG or in a rotary chair what cops test drunk drivers for
Term
 ENG
Definition
 electronystagmography a test to measure nystagmus
Term
 Shape of the Cochlea
Definition
 3.5 cm long - 1 cm wide part membrane & part bone 2 3/4 turns base to apex (large to small) similar to a snail & spiral stair case
Term
 Modiolus
Definition
 central core of cochlea made of bone osseous spiral lamina extends outward [image]
Term
 Osseous Spiral Lamina
Definition
 bony shelf that extends outward from the modiolus BM is connected wider at base & narrower at apex (opposite of BM)
Term
 Reissner's Membrane
Definition
 separates scala vestibuli from the scala media
Term
 Scala Vestibuli
Definition
 top section oval window & stapes footplate at base contains perilymph high in Na+ separated at bottom from scala media by the Reissner's membrane
Term
 Scala Media
Definition
 middle section of cochlea aka cochlear duct contains endolymph high in K+ shared with saccule of vestibule contains electro-mechanical transducing structures hair cells membranes support cells
Term
 Scala Tympani
Definition
 bottom section of cochlea contains perilymph high in Na+ round window at base separated at the top from scala media by basilar membrane
Term
 Basilar Membrane
Definition
 separates scala media from scala tympani provides a stiffness gradient narrow near base (.04 mm) stiffer higher resonant frequency wider at apex (.5 mm) looser lower resonant frequency logarithmic (nonlinear) the base is tuned to more frequencies than the apex
Term
 Stria Vascularis
Definition
 lateral wall of cochlea (opposite modiolus) no direct blood supply (despite the name) possibly a generator of endolymph
Term
 Spiral Ligament
Definition
 lateral wall of cochlea (opposite modiolus) support ligament for the stria vascularis
Term
 Organ of Corti
Definition
 in scala media made of sensory cells & support cells sits on BM covered by the TM
Term
 Support Cells in the Organ of Corti
Definition
 Deiter's cells Hensen's cells Claudius' cells Pillar cells inner supporting cells
Term
 [image]
Definition
 IHC OHC tunnel of Corti BM reticular lamina TM Deiter's cells space of Nuel Hensen's cells inner spiral sulcus
Term
 Sensory Cells in the Organ of Corti
Definition
 two types: IHC & OHC aka mechanoreceptors sense mechanical stimulation changes it to electrical/graded potential
Term
 Kinocilium
Definition
 rudimentary stereocilia thicker than regular stereocilia
Term
 [image]
Definition
 cilia at base of cochlea top row is IHC bottom 3 rows are OHC
Term
 Inner Hair Cells (IHC)
Definition
 one type of sensory cell in the Organ of Corti single row (3500) flask shaped - linear closest to modiolus not embedded in tectorial membrane shorter stereocilia senses movement of the endolymph high metabolic activity contain many Golgi & mitochondria supported by inner sulcus divergent neural pathway separated from OHC by pillars of Corti
Term
 [image]
Definition
 nucleus stereocilia cuticular plate radial afferent ending (dendrite) lateral efferent ending IHC
Term
 Hensen's Stripe
Definition
 the holes in the tectorial membrane for the stereocilia to fit
Term
 [image]
Definition
 nucleus stereocilia cuticular plate radial afferent ending (dendrite) lateral efferent ending medial efferent ending spiral afferent ending (dendrite) OHC
Term
 Convergent Neural Pathway
Definition
 many cells connect to one neuron OHC
Term
 Divergent Neural Pathway
Definition
 one cell connects to many neurons IHC
Term
 Pillars of Corti
Definition
 separate OHC from IHC
Term
 Afferent Neural Innervation of the Hair Cells in the Cochlea
Definition
 input from VIIIth nerve acoustic branch vestibular branch dendrites attach to the hair cells cell bodies are located outside of the cochlea in the spiral ganglion
Term
 Habenulae Perforata
Definition
 holes in the osseous spiral lamina where dendrites from the VIIIth nerve leave the cochlea
Term
 Efferent Neural Innervation of the Hair Cells in the Cochlea
Definition
 small bundles that innervate the OHC not much known except they get some kind of feedback
Term
 Cochlear Physiology
Definition
 detects sounds encodes information performs Fourier Analysis receives energy from stimulus uses energy to make some change in the sensory cell initiates some electrical activity in the nerve leading to the CNS
Term
 Mechanical Energy of the Ear
Definition
 vibratory passes through the middle ear stapes footplate vibrates in OW displaced fluid is released at the oval window http://www.iurc.montp.inserm.fr/cric/audition/english/ear/fear.htm
Term
 Hydromechanical Energy of the Ear
Definition
 pressure in the scala vestibuli creates pressure on scala media moves the BM (stiffness gradient)
Term
 Traveling Wave of the Cochlea
Definition
 travels from base to apex tonotopic organization maximum displacement at the point the BM is tuned to input frequency different frequencies are encoded at different places high frequences at base (20k Hz) low frequencies at apex (20 Hz) quickly dies off
Term
 Cuticular Plate
Definition
 sits on top of hair cells thickened plate with the phalange, they form the reticular lamina
Term
 Deiter Cell
Definition
 a support cell for the OHC cup-like each one has a phalange
Term
 Reticular Lamina
Definition
 a plate formed by the phalange plus the cuticular plate lies at the top of the hair cell, only the stereocilia stick above it
Term
 Inner Sulcus
Definition
 supports the inner hair cells
Term
 Movement of the TM and BM
Definition
 as BM moves up TM moves upward & away from modiolus as BM moves down TM moves downward & towards the modiolus
Term
 Tectorial Membrane (TM)
Definition
 sits on top of sensory cells in the Organ of Corti attached to the BM at the spiral limbus movement of the 2 membranes will be relative to each other connective tissue made of collagen jello-like mass has Hensen Stripes
Term
 OHC Stereocilia
Definition
 are embedded in the TM
Term
 IHC Stereocilia
Definition
 are affected by the movement of fluid under the TM
Term
 Actin Fibers
Definition
 attaches the stereocilia to one another found in muscle tissue & suggests movement
Term
 Prestin
Definition
 a contractile protein found in stereocilia & walls of OHC moves into OHC during depolarization & back into the walls during hyperpolarization
Term
 Stereocilia
Definition
 sit on top of IHC & OHC attached to one another via actin fibers move with fluid/membrane contains prestin are very rigid & the entire piece moves
Term
 Outer Hair Cells (OHC)
Definition
 sensory cell in the Organ of Corti three rows (12-16000) that are tube-shaped gradually gets larger from base to apex convergent neural pathway walls contain prestin contract when depolarizing & rotate at their base in the cups of the Dieter's cells elongate when hyperpolarize
Term
 Actin
Definition
 contractile protein that is very stiff stereocilia is made from
Term
 The Basilar Membrane Moves Up
Definition
 shearing of the OHC stereocilia the stereocilia move towards the kinocilium causes channels to open in the stereocilia K+ flows into cell from the endolymph causes the release of Ca++ within the stereocilia results in the release of myosin (contractile protein) contraction of stereocilia help them move back upright a chemical change (graded potential) occurs within the hair cell when K+ flows in
Term
Definition
 glutamate is released at the base of the hair cell it is absorbed by the neuron which is attached to the hair cell when enough is absorbed, depolarization occurs this causes a graded potential
Term
 Depolarization
Definition
 an electrical change (less negative) electro-mechanical transduction occurs when enough glutamate is absorbed by the neuron causes a graded potential
Term
Definition
 excitation of the neuron caused by depolarization
Term
 Hair Cell Neurotransmitters
Definition
 bottom of hair cell Glutamate efferent synapse Acetylcholin GABA Dopamine Enkephalins Dynorphins CGRP
Term
 As the Basilar Membrane Moves Down
Definition
 TM moves back towards the modiolus stereocilia move away from kinocilium aided by myosin causes the hair cell channels to close release of neurotransmitter is stopped hyperpolarization of the neuron which is inhibitory
Term
 Myosin
Definition
 contractile protein that causes cilia to contract & close channels results from the release of Ca++ when OHC channels open
Term
 Electromotility
Definition
 contraction during depolarization elongation during hyperpolarization due to prestin movement
Term
 Cochlear Potentials
Definition
 voltage change indicating activity resting potentials: endolymphatic potential intracellular potential summating potentials cochlear microphonic
Term
 Resting Potential
Definition
 no stimulus is needed 2 types: endolymphatic potential intracellular potential these two allow for a 150 mV difference across the top of the hair cell when channels open
Term
 Endolymphatic Potential (EP)
Definition
 one type of resting potential source is the endolymph from the stria vascularis in the scala media +80 mV charge at rest
Term
 Intracellular Potential (IP)
Definition
 one type of resting potential from inside the hair cell -70 mV charge at rest
Term
 Summating Potential (SP)
Definition
 only seen when acoustic stimulation is present source is unknown direct current shape always looks the same, regardless of stimulus  [image]
Term
 Cochlear Microphonic (CM)
Definition
 only seen when acoustic stimulation is present source is the root of the cilia on the hair cells alternating current reflects intensity & frequency of the input [image]
Term
 Otoacoustic Emissions (OAE)
Definition
 sounds produced by cochlea & sent out through the oval window, middle ear, & TM like an echo about -20 dB SPL reflects the OHC movement some evoked by a stimulus & others are spontaneous without a stimulus can be picked up by microphone in the ear canal
Term
 Evoked Otoacoustic Emissions
Definition
 produced by a stimulus 2 types: Transient evoked OAE Distortion product OAE
Term
 Transient Evoked Otoacoustic Emission (TEOAE)
Definition
 one type of evoked OAE produced by clicks response from cochlea 10-20 ms after stimulus only in healthy ears reflects hearing to about 30 dB not necessarily frequency specific won't be able to find hearing loss at specific frequencies used in newborn screenings
Term
 Distortion Product Otoacoustic Emissions (DPOAE)
Definition
 one type of evoked otoacoustic emissions produced by tones relies on the nonlinearities of the ear put in 2 tones, get a combination tone back summation/difference tones reflects normal hearing at the frequency range of the combination tone tests specific frequencies used in hearing testing & newborn screenings
Term
 Spontaneous Otoacoustic Emission
Definition
 near threshold only in healthy cochlea in 1/3 of the population
Term
 Auditory Nerve
Definition
 aka primary fibers because of its AP response afferent pathway (PNS to CNS) 30,000 fibers
Term
 Compound Potential
Definition
 when AP firing in the fibers of the auditory nerve takes place in synchrony
Term
 Spontaneous Discharge Rate
Definition
 continuous APs in each fiber of the auditory nerve no stimulus due to random release of neurotransmitters
Term
 Individual Fibers of the Auditory Nerve
Definition
 30,000 fibers 24 mm long (about 1 in) each has a characteristic frequency APs coming from each together can form a compound potential have a spontaneous discharge rate starts at the dendrites at the base of the hair cells 90-95% from IHC 5-10% from OHC
Term
 Type I Auditory Nerve Fibers
Definition
 aka radial fibers from IHC  90-95% of auditory fibers corresponds to more of a physiological load associated with the IHC 3 categories: High Spontaneous Rate Fibers Medium Spontaneous Rate Fibers Low Spontaneous Rate Fibers
Term
 Type II Auditory Nerve Fibers
Definition
 aka outer spiral fibers from OHC 5-10% of auditory fibers
Term
 High Spontaneous Rate Fibers
Definition
 one category of type I auditory nerve fibers >18 spikes/sec (no stimulus) large diameter synapse to lateral edge of IHC fires at low intensity sounds
Term
 Low Spontaneous Rate Fibers
Definition
 one category of type I auditory nerve fibers <.5 spikes/sec (no stimulus) small diameter synapse at medial edge of IHC fires at high intensity sounds
Term
 Medium Spontaneous Rate Fibers
Definition
 one category of type I auditory nerve fibers .5-18 spikes/sec (no stimulus) medium diameter synapse at inferior of IHC fires at middle intensity levels gradual intensity function (speech)
Term
 Auditory Nerve: Encoding Intensity
Definition
 tonotopically organized illustrated by different intensity functions of the different types of Type I fibers
Term
 Auditory Nerve: Encoding Frequency
Definition
 tonotopically organized high frequency fibers on outside (base) mid frequency fibers in middle low frequency fibers in the inside (apex) each fiber is tuned to a particular frequency its characteristic frequency shown by a tuning curve phase-locking response volley principle
Term
 Auditory Nerve: Characteristic Frequency (CF)
Definition
 each fiber is tuned to a particular frequency that excites it the most because of where it connects on the BM point on the tuning curve that corresponds to a frequency that the neuron fires to the lowest intensity
Term
 Tuning Curve
Definition
 graph with frequency on x-axis & intensity on y-axis the response area of a neuron discharge rate above spontaneous band-pass filter characteristics shows characteristic frequency steep high-freq side & less steep low-freq tail [image]
Term
 Auditory Nerve: Phase-Locking Response
Definition
 second way of encoding frequency firing patterns over time type of temporal coding found in frequencies up to 5000 Hz tends to happen at lower frequencies does not fire at every period chance of discharge is greatest at the same 90° phase the remaining half-cycle is probably inhibitory
Term
 Poststimulus Time Histogram (PST)
Definition
 graph that depicts phase-locked firing look how long it takes for a neuron to fire after the stimulus recorded in ms fire the most at the ms that is equivalent to 90° phase encodes frequency due to period information
Term
 Volley Principle
Definition
 third way of encoding frequency type of temporal coding high frequency phenomenon when a single nerve fiber reaches its maximum firing rate, it recruits other fibers to help fibers firing alternately, together increase the firing rate to a faster rate
Term
 2 Main Areas of the Central Auditory Nerve System
Definition
 Brain Stem midbrain pons medulla Brain (encephalon-cerebrum) telencephalon (cortex) hemispheres corpus callosum diencephalon (sub-cortical) thalamus
Term
 Brain Stem
Definition
 one main area of CANS most inferior structure contains pathways & way-stations or nuclei if there is a nuclei, there is processing taking place pathways are oversimplified multiple crossings from side-to-side
Term
 CANS: Cell Types
Definition
 different from auditory nerve which has a primary neuron response (AP) Choppers Onset Offset Pauser Build-up Cell
Term
 CANS: Chopper Cells
Definition
 on-off as in pulsing [image]
Term
 CANS: Onset Cells
Definition
 only fires at beginning of tone (stimulus)
Term
 CANS: Offset Cells
Definition
 only fires when tone (stimulus) ends
Term
 CANS: Pauser Cells
Definition
 fires at beginning & end of tone only [image]
Term
 CANS: Build-up Cells
Definition
 discharge rate increases during the duration of the stimulus
Term
 CANS: Neurotransmitters
Definition
 several present Acetylocholine GABA & Glycine Glutamate & Aspartate
Term
 Acetylcholine (Ach)
Definition
 neurotransmitter hair cells CANS both excitatory & inhibitory
Term
 GABA
Definition
 neurotransmitter hair cells CANS MSOC & LSOC IC LL inhibitory
Term
 Glycine
Definition
 neurotransmitter CANS LSOC IC LL inhibitory
Term
 Glutamate
Definition
 neurotransmitter hair cells CANS MSOC IC LL excitatory released at the base of the hair cell after shearing of the stereocilia takes place when enough is absorbed it causes depolarization
Term
 Aspartate
Definition
 neurotransmitter CANS MSOC excitatory
Term
 Cochlear Nucleus
Definition
 input from VIIIth CN function: intensity coding 2 divisions: dorsal cochlear nucleus ventral cochlear nucleus anterior posterior
Term
 Cochlear Nucleus: Intensity Coding
Definition
 preserves the coding (freq & intensity) of the VIIIth nerve processes the signal further some cells have large dynamic ranges (80-90 dB) some cells have smaller dynamic ranges (30-40 dB) many cells respond to amplitude-modulated signals respond to changes in the intensity
Term
 Cochlear Nucleus: Cell Types
Definition
 various types get multiple firing patterns codes temporal qualities of the stimulus octopus & bushy cells - phase-locked very sensitive to hyperbillirubenemia one cause of auditory neuropathy
Term
 Superior Olivary Complex (SOC)
Definition
 in the lower pons 2 divisions: medial (MSOC) lateral (LSOC) above cochlear nucleus, below lateral lemniscus
Term
 SOC: Intensity Encoding
Definition
 based mainly on binaural input (both ears) allows for larger response stimuli get complex interactions between inhibitory & excitatory neurons
Term
 SOC: Physiology
Definition
 first nuclei to get info from both ears lateralization when sound appears to move when using earphones localization creating the auditory space compares intensity & timing differences between ears
Term
 Lateral Superior Olivary Complex (LSOC)
Definition
 s-shaped low freq at dorsal/lateral high freq at ventral/medial interaural timing difference (ITD or ΔT) compares between ears contains 4 neurotransmitters
Term
 Medial Superior Olivary Complex (MSOC)
Definition
 c-shaped low freq at dorsal/medial high freq at ventral/lateral interaural intensity difference (IID or ΔI) compare between ears contains neurotransmitters
Term
Definition
 neurotransmitter MSOC & LSOC excitatory
Term
 Lateral Lemniscus (LL)
Definition
 major pathway through brain stem 4 different nuclei; 2 are primarily auditory ventral & dorsal commissure of Probst tonotopically organized
Term
 Ventral Nuclei of the Lateral Lemniscus
Definition
 primarily auditory sensitive to contralateral stimulation from the cochlear nucleus
Term
 Dorsal Nuclei of the Lateral Lemniscus
Definition
 primarily auditory sensitive to ipsilateral stimulation from superior olivary complex
Term
 Commissure of Probst
Definition
 lateral lemniscus connects dorsal nuclei on either side
Term
 Function of Lateral Lemniscus
Definition
 phase-locked coding (timing) not many different cell types not as precisely tonotopically organized plays a role in localization, particularly ITD neurotransmitters Glycine Glutamate GABA (large amounts)
Term
 Inferior Colliculus (IC)
Definition
 a group of nuclei most fibers originating from lower auditory nuclei synapse here different type and greater amount of processing occurs timing, freq, intensity, spatial domains not a simple relay station largest auditory structure of the brainstem in midbrain divided into 2 parts (belt organization): core pericentral nucleus cells in layers called lamina
Term
 Core of the Inferior Colliculus
Definition
 inner division only auditory fibers primary area
Term
 Pericentral Nucleus Division of the Inferior Colliculus
Definition
 outer layers lamina is tonotopically organized somatosensory & auditory fibers considered an association area
Term
 IC: Frequency Encoding
Definition
 highly tonotopic organization (lamina) narrow tuning curves high amount of freq resolution some have 2 characteristic freq (freq sweeps) responds more to tones & speech some cells are time sensitive, spatially sensitive, & binaurally sensitive
Term
 Inferior Colliculus: Intensity Encoding
Definition
 wide variety of cell responses some have large dynamic ranges (110 dB) some have smaller dynamic ranges (45-55 dB) some respond best at threshold
Term
 Inferior Colliculus: Temporal Processing
Definition
 amplitude modulated signals phase locking (sensitive to timing differences) many cells just respond to binaural stimulation some to ITD & some to IID some only fire at certain degrees (azimuths) gap deduction respond to small breaks in a signal
Term
 Inferior Colliculus: Neurotransmitters
Definition
 glutamate (excitatory) glycine & GABA (inhibitory)
Term
 Input & Output of the Lateral Lemniscus
Definition
 input: ipsilateral superior olivary complex  contralateral cochlear nucleus output: ipsilateral inferior colliculus (mostly) contralateral inferior colliculus contralateral lateral lemniscus
Term
 Input & Output of the Superior Olivary Complex
Definition
 input: contralateral cochlear nucleus (mostly) ipsilateral cochlear nucleus via acoustic stria output: contralateral & ipsilateral lateral lemniscus
Term
 MSOC: Neurotransmitters
Definition
Term
 LSOC: Neurotransmitters
Definition
Term
 Input & Output of the Cochlear Nucleus
Definition
 input: auditory branch of the VIIIthe cranial nerve output: contralateral superior olivary complex (mostly) ipsilateral superior olivary complex ipsilateral inferior colliculus
Term
 Pinna's Increase in Amplification
Definition
 3-4 dB at 3k-4k Hz
Term
 Concha's Increase in Amplification
Definition
 10-15 dB at 1.5k to 7k Hz
Term
 External Auditory Canal's Increase in Amplitude
Definition
 10-15 dB at 2.5k Hz
Term
 Medial Geniculate Body
Definition
 a nucleus of the thalamus inferior colliculus' main pathway output to cortex (Heschl's gyrus) frequency coding tonotopically organized intensity coding monotonic 1/4 respond to one frequency nonmonotonic 3/4 respond to several frequencies temporal coding main job tend to fire to groups of stimuli
Term
 Heschl's Gyrus
Definition
 input from medial geniculate body #41 & #42 primary area of the auditory cortex frequency & intensity coding ipsilateral & contralateral responses very sensitive to temporal changes responses seem to be boosted
Term
 Auditory Cortex
Definition
 telecephalon - hemispheres 6 cell layers deep (each has own function) 4th layer receives input from MGB also columnar organization tonotopic - each block encodes something different
Term
 Primary Area of Auditory Cortex
Definition
 #41 (Heschl's gyrus) temporal lobe within Sylvian fissure far more arborization (dendrites) & auditory responsive neurons than any other place in CANS
Term
 Association Area of the Auditory Cortex
Definition
 surrounding the primary area close to Wernicke's #22 Arculate Fasciculus Superior Temporal Plane Planum Temporale
Term
 Arculate Fasciculus
Definition
 association area of the auditory cortex major fiber tract that travels through temporal lobe, Wernicke's to the frontal lobe to Broca's
Term
 Planum Temporale
Definition
 association area of the auditory cortex next to Heschl's gyrus  language related larger in left hemisphere possibly receptive language site
Term
 Corpus Callosum
Definition
 last stop connects right and left hemispheres very large 6.5 cm long & .5-1 cm thick heavily myelinated axons (complete at 12 yrs) otherwise will not transmit info well mostly homolateral (e.g. connects Heschl's gyrus on left to Heschl's gyrus on right) right ear advantage
Term
Definition
 contralateral pathways are dominant left hemisphere is dominant for language stimulus travels from right ear to left hemisphere, but left ear travels to right hemisphere then left not seen in adults myelination is complete so info travels faster
Term
 Binaural Hearing
Definition
Term
 Localization
Definition
 locating source of sound in environment accomplished by comparing input from both ears interaural time differences interaural intensity differences done by assigning source of sound to a degree in the azimuth plane
Term
 Azimuth Plane
Definition
 circle around head parallel to floor front - 0° right - 90° back - 180° left - 270°
Term
 Interaural Time Differences (ΔT)
Definition
 applies to localization which ear receives the stimulus first 90° = max at .65 ms 0° & 180° = plane of confusion very predictable measured in ms used in low frequencies related to wavelength as frequency decreases, wavelength increases makes it easier to tell when the waveform begins
Term
 Interaural Intensity Differences (ΔI)
Definition
 applies to localization which ear receives the greatest intensity get up to 20 dB difference applies to higher frequencies (+4k Hz)
Term
 Duplex Theory
Definition
 applies to localization combination of delta T & delta I works for pure tones & complex signals doesn't account for reflections
Term
 Precedence Effect
Definition
 Law of the First Wavefront ear/brain uses the first arriving set of information & ignores echos and reverberations
Term
Definition
 we hear better in noise with two ears over one shown in experiment called Masking Level Difference
Term
Definition
 SoMo (65) - SπMo (45) = 20 dB experiment for binaural masking compares thresholds in different listening conditions monotic diotic dichotic S = signal M = masker o = both ears m = one ear π = one ear at 180° out-of-phase the other at 0°
Term
 So
Definition
 signal identical in both ears diotic
Term
 Mo
Definition
 masker identical in both ears diotic
Term
 Sm
Definition
 signal in one ear monotic
Term
 Mm
Definition
Term
 Sπ
Definition
 signal in one ear at 180° and 0° in the other simultaneously receiving a different signal in each ear dichotic
Term
 Mπ
Definition
 masker in one ear at 180° and 0° in the other simultaneously receiving a different masker in each ear dichotic
Term
 Monotic
Definition
 signal & masker going in one ear SmMm
Term
 Diotic
Definition
 same signal & same masker going in both ears SoMo
Term
 Dichotic
Definition
 SπMo different phase signal & same masker in both ears SπMm out-of-phased signals & the same masker in both ears SπMπ different phased signal & different phased masker in both ears SoMπ same signals but different phased maskers in both ears SmMπ a signal in one ear & different phased maskers in both ears
Term
 Binaural Summation
Definition
 get an added 3 dB of intensity when we use both ears
Term
 Helicotrema
Definition
 end of the cochlea tube connects the scala tympani and scala vestbuli
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