Audition Frequency and Amplitude

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AuditionFrequency and Amplitude

• Audition
• the sense of hearing
• Frequency
• the number of complete wavelengths that pass a
  point in a given time pitch
• Pitch (wave frequency, Hz)
• High frequency high pitch
• low frequency low pitch

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Amplitude

• Amplitude height of sound wave loudness of
  sound
• Timbre quality, complexity of sound
• Average human hears tones from 20Hz to 20,000Hz.
  
• Women tend to hear higher frequencies
• Theory men Louder activities more often

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The Intensity of Some Common Sounds
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From Waves to Sound

• Outer Ear
• Channels sound wave through auditory canal to
  eardrum
• Middle Ear
• Eardrum Membrane/ converts wave to vibrations
• Vibrations pass through piston (hammer, anvil,
  stirrup smallest bones in human body!) piston
  concentrates vibrations of the eardrum on the
  cochleas oval window
• Inner Ear
• Cochlea converts vibrations into neural activity
  (vibration ripples in basilar membrane fluid
• Bending hair cells auditory neural impulse

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In other words

• From sound waves to vibrations to fluid waves to
  neural impulse to auditory cortex (temporal lobe)
  hearing!

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Hair Cells Basilar Membrane
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How do we discern pitch?

• Place Theory
• Specific places along the basilar membrane match
  a tone with a particular pitch
• Frequency Theory
• rate of sound wave rate of neural impulses to
  the brain ( of neural impulses determines pitch)
  ex. 100 sound waves/second 100 neural impulses
  pitch)

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How We Locate Sounds

• Brain analyzes differences in what is heard by
  each ear to determine where sound is coming from
  (3 dimensional)

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Hearing Loss

1. Most common physical disability
2. 35 million Americans (500 million worldwide)
3. Recent study 60 of American college students
   suffer from high frequency hearing loss.
4. Each 5 db increase, time it takes for permanent
   damage cut in half (after 85)
5. Men greater degree of hearing loss at every age
   (loud music or changes in cochlea that restrict
   blood supply to neural elements?)

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Audition

• Conduction Hearing Loss
• caused by damage to the mechanical system that
  conducts sound waves to the cochlea (Ear drum,
  hammer, anvil, stirrup)
• Nerve Hearing Loss
• hearing loss caused by damage to the cochleas
  receptor cells or to the auditory nerve (hairs in
  basilar membrane not regenerative)

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Tinnitus

• Damage to auditory ear (ringing in ears)
• Advanced case is incapacitating
• Shell shock (combat zones)
• tinnitus masker ocean waves or radio static

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Helen Keller

• What would be more difficult, being blind or
  deaf?
• deafness to be a much greater handicap than
  blindness Blindness cuts people off from things.
  Deafness cuts people off from people.

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Cochlear Implants

• Nerve deafness
• bionic ear
• Stimulates sites on auditory nerve

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Audition

• Older people tend to hear low frequencies well
  but suffer hearing loss for high frequencies

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True or False?

• 1. Hard of hearing people need all sounds
  amplified.
• 2. Blind musicians are more likely than sighted
  ones to develop perfect pitch.
• 3. Deaf peoples auditory cortex becomes
  responsive to touch and visual input.
• Sensory Compensation / plasticity

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Touch

• Skin senses pressure, warmth, cold, pain
• Which is the only sensation identifiable with
  skin receptors?
• Pressure
• The Rubber hand illusion (demo)

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Touch
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Pain

• Pain sensation brain expectation
• No brain, no pain
• More complex / no one stimulus / neural cord, no
  special receptors
• Research shows extent of pain is more influential
  than duration (medical procedures)

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Pain

• Gate-Control Theory
• Theory spinal cord contains a neurological
  gate that blocks pain signals or allows them to
  pass on to the brain
• Small nerve fibers conduct pain signals
• Small nerve fibers open / activate neural gate
• Large nerve fibers close gate (shut off pain)

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Chronic Pain

• Pain physiological and psychological
• Treat by stimulating large neural fibers (to
  close the gate)
• Acupuncture, massage, electrical stimulation)
• 1 in 6 Americans100 billion total expenses

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Reactions to pain..

• Why do we rub something when we hurt it?
• Create competing stimulation that will block some
  of the pain impulses (Makes it feel better)

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Taste

• Taste Sensations
• sweet
• sour
• salty
• Bitter
• Umami (meaty taste) monosodium glutamate
• Sensory Interaction
• the principle that one sense may influence
  another (all senses)
• Ex the smell of food influences its taste

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Taste A Chemical Sense

• Each bump on your tongue 200 taste buds
• Taste sensitivity decreases with age
• Sensory interaction taste texture smell
  flavor
• T-F
• You can taste without your tongue.
• (Taste receptors in back and roof of mouth.)

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New Studies

• Tongue and taste Place theory outdated
• Taste is comprehensive over tongue

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Senses Influence Each Other

• Sensory Interaction
• the principle that one sense may influence
  another (all senses)
• Ex the smell of food influences its taste
• Synaesthesia (to perceive together)
• joining of senses / one sense stimulates another
• Feels shapes when taste / smell food
• See colors in response to pain
• Most common see numbers / letters in colors
• Recent study 1 in 2,000 - 1 male to 6 female
• Theory cross-activation of adjacent brain
  regions

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Smell

• Olfaction
• A chemical sense
• Process
• Molecules of substance / air / 5 million receptor
  cells _at_ top of each nasal cavity
• Impulse sent to brain through axon fibers
• Odors recognized individually
• Odor molecules / neural receptors (key and lock)
• 10,000 odors detected! Peak at early adulthood
• Olfactory bulb gt amygdala gt hippocampus gt cortex
  (why smell evokes emotions, memories)

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Smell
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Gender and Senses

• Detecting men from women smell
• Research confirms hands, breath and shirts-
• can distinguish the genders (pheromones)
• Women better sniffers than men

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Age, Sex and Sense of Smell
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Body Position and Movement(Sensorimotor
Coordination)

• Kinesthesis
• the system for sensing the position and movement
  of individual body parts
• Vestibular Sense
• Monitors head (and thus bodies) movement
• Sense of balance (equalibrium)
• Inner ear semicircular canals, vestibular sacs
  fluid hair-like receptors impulse to
  cerebellum (Vertigo)

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Make sense now?