Sensation Hearing and Other Senses

1. SensationHearing and Other Senses AP Psych, Myers, Ch. 5

2. Audition and the Ear

3. 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

4. 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

5. Outer Ear Pinna – outer ear/lobe • External auditory canal – channels sound waves to the eardrum

6. Middle Ear – eardrum, 3 bones • Eardrum – thin membrane that vibrates when a sound waves hits it • Vibrations felt by 3 small bones – hammer, anvil, and stirrup – and sent to inner ear

7. 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

8. How Do We Hear Pitch? Audition and Pitch Theories Cochlea Animation Place Theory (Helmholtz) Frequency Theory • 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 We use both theories to hear all pitches.

9. Locating Sounds • Distance between ears allows us to place sounds in space. • Equidistant sounds – cock our heads to distinguish location

10. 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 • device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea. • Must have a functioning auditory nerve

11. Cochlear Implants • Pro • Con • 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 • Deafness is not a disability • ASL is a complete and functioning language • Deafness ≠ linguistically impaired

12. 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

13. Other 3 Senses Olfaction, Taste, Touch

14. 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

15. 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

16. Gustation – Sense of Taste Wrong • 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”)

17. 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)

18. 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

19. Flavor • Combination of odor, texture, temperature, and taste • “taste blindness” – lack of sensitivity to certain taste • Sensitivities can be inherited Tea Flavors Chocolate Flavors

20. 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

21. Touch Pathway • Skin receptors (transduction)  nerves (PNS)  spinal cord (CNS)  medulla  thalamus  sensory cortex

22. Pain • Something is WRONG! • Psychological • Attention to pain • Learning based on experiences • Expectations of pain • Social Cultural • Presence of others • Empathy for other’s pain • Cultural expectations • 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 Perception of Pain

23. 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

24. 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

25. The 6th and 7th Senses Kinesthesis and Vestibular Sense

26. 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)

27. 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)