AUDITION – THE SENSE/ACT OF HEARING
We hear via sound waves Loudness –
strength/amplitude of wave (measured in decibels – dB) Loud sounds have high
amplitudes softer sounds have smaller
amplitudes
AUDITION – THE SENSE/ACT OF HEARING
Pitch – a tone’s experienced highness or lowness, depends on frequency Frequency – number of wavelengths that pass a
point in a period of time Low frequency sounds = bass High frequency sounds = high ringing
MIDDLE EAR – EARDRUM, 3 BONES
Eardrum – thin membrane that vibrates when a sound waves hits it Vibrations felt by 3
small ossicle bones – hammer, anvil, and stirrup – and sent to inner ear
INNER EAR - COCHLEA, SEMICIRCULAR CANALS, AND VESTIBULAR AREAS
Cochlea – a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses Moving fluid in cochlea
triggers hair cells in the cochlea’s basilar membrane stimulates neurons to produce electrical impulses
Auditory nerve – sends neural impulses from the cochlea to the brain (thalamus temporal lobe)
Hearing Animation
HOW DO WE HEAR PITCH?
Links the pitch we hear with the place where the cochlea’s membrane is stimulated
High pitch sounds
The rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch
Low pitch sounds
Place Theory (Helmholtz) Frequency Theory
Audition and Pitch Theories
Cochlea Animation
We use both theories to hear all
pitches.
LOCATING SOUNDS
Distance between ears allows us to place sounds in space.
Equidistant sounds – cock our heads to distinguish location
HEARING LOSS
Conduction Damage to the mechanical
elements (eardrum, H, A, or S) that conduct sound waves to the cochlea
Sensorineural Damage to the cochlea’s receptor
cells or to the auditory nerve, also called nerve deafness
Hearing can be slightly restored with a cochlear implant (if there is a healthy nerve) device for converting sounds into
electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.
Must have a functioning auditory nerve
COCHLEAR IMPLANTS
Pro Experience sounds
and oral communication
Helps deaf children with talking
Children who rely solely on ASL before learning to speak have more difficulty learning to read and write later in life
Con
Deafness is not a disability
ASL is a complete and functioning language
Deafness ≠ linguistically impaired
SENSORY COMPENSATION
People who lose one channel of sensation often compensate for it with a slight enhancement of other sensory abilities
Also a product of brain plasticity
OLFACTION – SENSE OF SMELL Chemical sense - Odors
are composed of chemical molecules which are sensed by olfactory receptor cells at the top of the nasal cavity.
Receptors in nasal cavity (transduction) olfactory bulb olfactory nerve primary smell cortex (temporal lobe) only sense not to pass
through the thalamus
OLFACTION AND MEMORY/EMOTION
Odors invoke memories or feelings because the part of the brain that interprets odors is directly linked with the limbic system which processes memories and emotions
GUSTATION – SENSE OF TASTE
Evolutionary purpose – survival
5 basic tastes Sweet Salty Sour Bitter Umami (best experienced by the flavor enhancer MSG, most
commonly found in Asian food – described as “savory”)
Wrong
GUSTATION - TASTE
Chemical sense – taste buds (200+ per bump on tongue) catch food chemicals via receptor cells Receptor cells can be more
sensitive to different tastes
Receptors on taste buds (transduction) facial nerve medualla thalamus primary gustatory region (temporal lobe)
SENSORY INTERACTION
The principle that one sense may influence another, as when the smell of food influences its taste To savor taste we normally breathe the aroma
through the nose Sight of spoken words and the audition of spoken
words influence each other
Vision and audition We use the auditory info from the sound of words
and the visual info from the moving of the mouth to quickly comprehend speech.
However, this sensory interaction can also lead us astray…
FLAVOR Combination of odor, texture, temperature, and
taste “taste blindness” – lack of sensitivity to certain taste Sensitivities can be inherited
Tea Flavors
Chocolate Flavors
TOUCH - SKIN SENSES
4 distinct skin senses Pressure Warmth Cold Pain These senses are combined to produce
sensations such as: hot, tickling, itchy, wetness, etc
Only the sensation of pressure has specialized nerves in the skin; the rest of the nerve endings can feel warmth, cold, and pain in various combinations
TOUCH PATHWAY
Skin receptors (transduction) nerves (PNS) spinal cord (CNS) medulla thalamus sensory cortex
PAIN
Something is WRONG!
Perception of Pain
Biological•Activity in spinal cord’s large and small fibers (gate-control theory)•Genetic differences in endorphin production•The brain’s interpretation of CNS activity
Psychological•Attention to pain•Learning based on experiences•Expectations of pain
Social Cultural•Presence of others•Empathy for other’s pain•Cultural expectations
GATE-CONTROL THEORY
The spinal cord acts as a gate that controls if pain signals reach the brain. Small nerve fibers conduct pain signals, while larger
neural fibers conduct most other sensory signals. When tissue is injured, the smaller nerve fibers activate
and open the neural gate to send pain to the brain. Larger-fiber activity closes the pain gate, turning pain
off.
Using this theory, people believe that activating large neural fibers can block pain Ex: acupuncture Ex: rubbing painful areas stimulates large neural fibers
than can block pain Ex: electrical stimulation of painful area
PAIN CONTROL
Pain can be treated physically and psychologically Drugs, surgery, acupuncture, electrical
stimulation, massage, exercise, hypnosis, relaxation training, thought distraction, etc
Because pain is perceived in the brain, diverting the brain’s attention can bring relief
KINESTHESIS
AKA Proprioception The system for sensing the
position and movement of individual body parts Enabled by millions of
proprioreceptors in muscles, tendons, and joints
Proprioreceptors (transduction) nerves spinal cord brain (cerebellum)
VESTIBULAR SENSE
The sense of body movement and position, including the sense of balance Monitors the head’s position which usually dictates
what the body is doing
Fluid in semicircular canals hair cells in vestibular sacs vestibular nerve brain (medulla and cerebellum)