Physiology of the Auditory System Flashcards
Number of cycles per second (Name and Unit of Measurement)
Frequency * Hertz (Hz)
Inverse of frequency, duration of a single cycle
Period
Maximum amount of displacement from the null point in one direction
Amplitude
Sound produced by simple harmonic motion
Pure tone
T or F: Sound travels faster in air.
F * Dry Air: 340m/sec, Water: 1500m/sec
Vibration that is not simple harmonic motion
Complex vibration
Complex vibration with repetitive periodic pattern
Tone
Complex vibration with no repetitivr pattern
Noise
Amount of force that vibrating sound particles exert on a surface area (Name and measure)
Sound pressure * Pascals (Pa), also equals the square root of intensity
Intensity is measured in____?
Decibels (dB)
Frequency where stiffness and mass components of acoustic impedance cancel each other out
Resonance frequency
Resonant frequency of 1) concha, 2) EAC
1) 5300 Hz, 2) 3000 Hz
Sound coming from one side is attenuated by the head as it travels to the contralateral ear
Head shadow effect
Important for low frequency sound localization
Interaural TIME difference
Important for high frequency sound localization
Interaural AMPLITUDE difference
Identify this pathway to sound transmission: sound goes to the inner ear in the absence of the ossicular system
Acoustic coupling
Identify this pathway to sound transmission: Malleus is coupled to the TM. Vibration of the TM causes entire ossicular chain to vibrate. Sound is transmitted to the inner ear via the stapes footplate.
Ossicular coupling
Name the 2 mobile joints of the ossicular chain and their types.
Incudomalleal, Incudostapedial * Synovial joints are also called Diarthrotic joints
Difference between ossicular coupling and acoustic coupling in Db
60 dB * Maximal amount of hearing loss in ossicular diacontinuity
This term denotes maximizing sound transfer
Impedance matching
Most important factor in middle ear’s impedance matching capability
Area ratio (26 dB)
Second mechanism for impedance matching due to the manubrium being slightly longer manubrium than long arm of incus - - a slight force on the manubrium (long arm of lever) results in a greater force in the long process of the incus (short arm of lever)
Lever ratio (2.3 dB)
1) Theoretical 2) Actual middle ear sound pressure gain
1) 28dB, 2) 20dB * Actual gain is lower because the TM does not move as a rigid diaphragm, it vibrates in a complex manner. The effective area of TM involved with impedance matching is smaller than the total area
Impediment to movement, ratio of acoustic pressure to the volume velocity generated by acoustic pressure
Impedance * Increased in fluid vs. Air
Frequency where stiffness and mass components of acoustic impedance cancel each other out
System is in resonance
Flask shaped, 3000 in number, arranged in a single row
Inner HC
Cylindrical, 12000 in number, arranged in 3-4 rows
Outer HC
This part is affected by movement of stapes on oval window (Scala?)
Vestibuli
Basilar membrane is ____ stiff near the base and is more sensitive to _____ pitch
More, high
Basilar membrane is ____ stiff near the apex and is more sensitive to _____ pitch
Less, lower
This phenomenon involves shunting of acoustic energy away from the cochlea, leading to decreased sensitivity to AC sound and airbone gap seen on audiometry
Third window * Sup SCC syndrome, enlarged vestibular aqueduct, inner ear malformation
Stereocilia deflected towards tallest row leads to
Depolarization
Stereocilia deflected away tallest row leads to
Hyperpolarization
OHC contracts during
Depolarization
OHC elongates during
Hyperpolarization
Also known as cochlear amplifier
OHC
Bipolar, large, myelinated, 95%, synapses with SINGLE IHC
Type I spiral ganglion cells
Smaller, un or myelinated, 5%, synapses with MULTIPLE OHC
Type II spiral ganglion cells
High spontaneous neurons are best for these types of sounds
Low level sounds due to low threshold
Low spontaneous neurons are best for these types of sounds
High level sounds due to their wide dynamic range
First relay station for all ascending auditory information
Cochlear nucleus * In the pontomedullary junction
Fiber tracts that project contralaterally to the inferior colliculus
Lateral lemniscus
Relay station for binaural hearing
Superior Olivary Complex * Pons
Area with important role in sound localization by determination of interaural time and amplitude difference
Superior Olivary Complex
Ability to increase signal to noise ratio in binaural hearing
Binaural squelch
Ability to receive sound signals in greater amplitude in binaural hearing
Summation
Integrates information from auditory and nonauditory sources, also receives info on interaural time and amplitude differences, sends fibers to thr medial geniculate body of the thalamus
Inferior colliculus
Involved in sound localization and processing of complex vocal communication
Medial geniculate body
Division of the medial geniculate body that projects to the 1) primary 2) secondary auditory cortex
1) ventral 2) dorsal
Broadmann area of 1) primary auditory cortex, 2) auditory association area, 3) Wernicke area
1) 41, 2) 42, 3) 22
Speech _______: 1) Wernicke, 2) Broca
1) reception, 2) production
Other areas of the brain receiving auditory information (2)
Amygdala, Limbic System
Stapedius reflex pathway Cochlea to Stapes (7)
Cochlea, Cochlear Auditory nerve, Cochlear Nuclei, Stapedius Motoneurons, Facial Nerve, Stapedius, Posterior neck of stapes capitulum
Primary sound evoked middle ear muscle
Stapedius * Tensor tympani plays a minor role
Startle reaction is associated with this middle ear muscle
Tensor tympani
1)Location, 2)Attachment, 3)Innervation of Tensor Tympani
Above ET, neck of manubrium, V3
Olivocochlear pathway that innervates 1)OHC, 2) IHC
1)Medial Low freq sound, 2)Lateral high frequency sound (unclear role)
This pathway decreases cochlear responses by decreasing the gain by hyperpolarization of the OHC (protect ears from acoustic trauma), also decreases auditory responses to the background noise
Medial Olivocochlear Complex Pathway
