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  1. The physical stimulus for audition is the;
    sound wave
  2. Sounds are created when;
    objects vibrate
  3. Area of refractions-
    when there is a lot of room between molecules
  4. Compression
    air molecules are compacted together
  5. Less frequency waves=
    lower sounds
  6. Frequency
    • Number of pressure changes per cycle
    • Measured in hertz (Hz)
  7. 1Hz =
    one cycle per second
  8. Pitch
    Our perception of frequency
  9. Amplitude
    • Amount of change in pressure
    • Also called intensity
    • Measured in decibels (dB)
  10. Loudness
    Our perception of amplitude
  11. Decibels
    • measures the physical intensity of sound
    • Logarithmic scale
  12. Reletively small decibel changes can correspond to;
    large physical changes
  13. An increase in 6dB;
    Doubles the amount of sound pressure
  14. Typical threshold is;
    1-2 dB
  15. Complexity
    • Number of different frequencies in a sound
    • Physical
  16. Fundamental
    • lowest frequency
    • Determines pitch
  17. Harmonics
    Higher pitched tones related to the fundamental (makes things sound good or bad)
  18. Fourier Analysis and Hearing:
    Any complex tone can be represented as a series of simple tones (sine waves)
  19. Fundamental + 2nd harmonic + 3rd harmonic =
    composite wave
  20. Ohm's Law
    Because the auditory system does a Fourier analysis on complex tones, we are aware of each of the simple tones
  21. Timbre
    Our perception of complexity
  22. Timbre is created by the kind and number of;
  23. Rich, full sounds (violin, voice) have;
    many overtones or harmonics
  24. Pure, thin sounds (flute) have;
    few overtones
  25. Phase
    • The reletive position of two or more sine waves
    • physical
    • means where the wave is in compression - rare fraction cycle
  26. In-phase:
    Peaks occure at the same time (troughs)
  27. Out of phase:
    occur at different time
  28. Noise Cancellation
    • Destructive interference
    • Sound waves can cancel each other out if they are 180 degrees out of phase
    • Cars and cell phones are doing this
  29. Resonant Frequency
    • The frequency with which an object vibrates when hit
    • Knocking on the body of a cello (strings start to vibrate)
  30. Because of Resonant Frequency an object:
    will begin to vibrate if a sound wave matching the object's resonant frequency travels close to the object = resonant
  31. Pinna
    The outer funnel-like part of the ear
  32. Ear Canal
    The canal that conducts sound vibrations from the pinnato the tympanic membrane and prevents damage to the tympanic membrane
  33. Tympanic membrane
    • The eardrum
    • A thin sheet of skin at the end of the outer ear canal.
  34. The tympanic membrane vibrates;
    in response to sound
  35. Outer ear
    the external sound gathering portion of the ear, consisting of the pinna and the ear canal
  36. Middle Ear
    an air filled chamber containing the middle bones or ossicles
  37. The middle ear conveys and amplifies
    vibration from the tympanic membrane to the oval window
  38. Ossicles
    Three tiny bones of the middle ear; malleus, incus, and stapes
  39. Malleus
    • one of the ossicles
    • Receives vibration from the tympanic mem. and is attached to the incus
  40. Incus
    • The middle ossicle
    • Connects the malleus and stapes
  41. Stapes
    Connected to the incus on one end, the stapes presses against the oval window of the cochlea on the other end
  42. Oval Window
    The flexible opening to the cochlea through which the stapes transmits vibration to the fluid inside
  43. Inner ear
    A hollow cavity in the temporal bone of the skull and the structures within this cavity: the cochlea and vestibular canals
  44. Tensor Tympani
    the muscle attached to the malleus
  45. Tensing the tensor tympani;
    decreases vibration
  46. Stapedius
    • The muscle attached to the stapes
    • tensing this muscle decreases vibration
  47. Acoustic reflex
    A reflex that protects the ear fromintense sounds, via contrasction of the stapedeus and tensor tympani muscles
  48. Cochlea
    A spiral structure of the inner ear containing the oran of corti
  49. Tympanic Canal
    • One of three fluid filled passages in the cochlea.
    • It extends from the round window at the base o the cochlea to the helicotrema at the apex
    • Also called scala tympani
  50. Vestibular Canal
    • one of three fluid filled passages in the cochlea
    • Extends from the oval window to the helicotrama at the apex
    • Scala Vestibula
  51. Middle Canal
    • One of three fluid filled passages in the cochlea
    • Is sandwiched between the tympanic and vestibular canals and contains the cochlear partition
    • Scala Media
  52. Helicotrema
    The opening that connects the tympanic and vestibular canals at the apex of the cochlea
  53. Reissner's Membrane
    A thin sheat of tissue separating the vestibular and middle canals in the cochlea
  54. Basilar Membrane
    A plate of fibers that forms the base of the cochlear partition and separates the middle and tympanic canals in the cochlea
  55. Cochlear Partition
    the combines basilar membrane, tectorial membrane, and organ of corti, which are together responsible for the transduction of sound waves into neural signals
  56. On top of the Basilar mem. is the
    organ of corti
  57. Hair Cells
    • Transduce mechanical movement in the cochlea in to neural activity
    • 3500 inner cells and 10,500 outer hair cells
  58. 95% of auditory nerve cells connect with;
    inner hair cells
  59. Inner hair cells are;
    Afferent (sending)
  60. Outer hair cells are;
    Efferent (receiving)
  61. Function of Outer hair cells
    • Sharpen information sent by inner cells (receive info. about which frequencies need to be heightened or amplified)
    • Amplifies sounds
  62. Otoacoustic Emissions
    • Sound produced just by your ear, nothing else.
    • Can be used to test newborn's hearing
  63. Hair cells are tuned to specific frequencies called;
    Tonotopically organized
  64. Place Theory
    • Hair cells are tonotopically organized on basilar membrane
    • Low frequencies cause maximal displacement furthest from the oval window (apex)
    • High frequencies cause max displacement closest to oval window (base)
  65. How he determined place theory
    he got cochlea from fresh cadavers and cut windows in it, played tones to see if basilar mem. moved - high frequencies
  66. Place Theory has to do with;
  67. The lower the sound,
    the less likely it will be to be a crisp sound
  68. Problem with place theory
    dont see nice neat traveling waves for low frequency sounds
  69. Temporal Code theory mainly deals with;
  70. Temporal Code theory
    Frequency of sound is coded by how many times auditory neurons fire
  71. Phase locking
    Firing of a single neuron at one distinct point in the cycle of a sound wave
  72. Problem with Temporal Code Theory
    • There arent enough hair cells to be tuned for all frequencies
    • Nerve cells can only fire up to 1000 times
  73. Solution to Temporal code theory
    • Cells work in groups to code frequency
    • Look at total output of group of cells to determine frequency of sound
  74. Temporal Theory summary
    • Frequency coded by the sum of action potentials produced by a group of cells
    • Amplitude coded by determining how many cells in that group are firing at the same time
    • The more cells firing means the louder the sound
  75. Cooperation of Place and Temporal Code theory
    • High frequencies: place theory (above 3000Hz)
    • Low frequencies: temp. theory (below 1000 Hz)
    • Between 1000 and 3000 Hz: both theories work
    • Both theories say the same thing about amplitude
  76. Threshold Tuning Curve
    A map plotting the thresholds of a neuron or fiber in response to sine waves with varying frequencies at the lowest intensity that will give rise to a response
  77. Volley principle
    An idea stating that multiple neurons can provide a temporal code for frequency if each neuron fires at a distinct point in the period of a sound wave but doesnt fire on every period
  78. Cochlear Nucleus
    the first brain stem nucleus at which afferent auditory nerve fibers synapse
  79. Superior Olive
    an early brain stem region in the auditory pathway where inputs from both ears converge
  80. Medial Geniculate Nucleus
    the part of the thalamus that relays auditory signals to the temporal cortex and receives input from the auditory cortex
  81. Tonotopic Organization
    an arrangement in which neurons that respond to different frequencies are organized anatomically in order of frequency
  82. Conductive hearing loss
    hearing loss caused by problems with the bones of the middle ear
  83. Otitis Media
    inflammation of the middle ear, commonly in children as a result of infection
  84. Otosclerosis
    abnormal growth of the middle ear bones that causes hearing loss
  85. Ototoxic
    producing adverse effects on organs or nerves ivolved in hearing or balance
Card Set:
2011-11-15 15:35:38

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