Hearing and Other Senses

Frequency

-High frequency->short wavelengths(high pitched)
-Low frequency-> long wavelengths (low pitched)

Amplitude

-great amplitude-> tall height (loud)
-small amplitude-> short height (quiet)

3 divisions of the ear

outer, inner, and middle

auditory canal

-outer ear
-funnels sound waves from the pinnal to the eardrum

Eardrum

- thin layer of tissue that vibrates because of sound waves

Ossicles

\-3 tiny bones in the ear

* incus-→Anvil
* malleus → Hammer
* stapes→ stirrup
* transfers sound waves from the eardrum to the oval window of the cochlea

Cochlea

-coiled, bony, fluid filled in the inner ear
- sound waves travel through the cochlea luid and triggers nerve impulses

Sensorineural Hearing loss

- damage to the auditory nerve
-people can hear the sound, but they have trouble understanding what they are saying
-this loss generally occurs when some of the hair cells within the cochlea are damaged.

Conduction Hearing loss

-damage to the eardrum and middle ear bones that conduct sound waves to the cochlea

Cochlear implant

-a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

How does brain detect loudness

-the brain interprets loudness from # of activated hair cells

Place theory

-Proposes that different areas of the cochlea respond to different frequencies.
-Higher tones excite areas closest to the opening of the cochlea (near the oval window).
-Lower tones excite areas near the narrow tip of the cochlea, at the opposite end.

Frequency Theory

-Whatever the pitch of a sound wave, nerve impulses of a corresponding frequency will be sent to the auditory nerve.
-exp: a tone measuring 600 hertz will be transduced into 600 nerve impulses a second.

How to sense touch

-pressure, hot, cold, and pain

Gate control theory

- suggests that the spinal cord contains a neurological 'gate' that either blocks pain signals or allows them to continue on to the brain.
-This theory is often used to explain both phantom and chronic pain issues

Chemical senses

-taste(gustation)
-smell(olfaction)
because their function is to monitor the chemical content of the environment.

5 basic taste

-sweet
-salty
-sour
-bitter
-umami

Sense of smell

-olfaction-> 20 million olfactory receptors respond
selectively to aroma of baking a cake, wisp of smoke, etc.
-where odors are transduced to neural messages for the brain
-they instantly alert the brain with there axon fibers

Kinesthetic sense

-feeling the movement of limbs and joints
exp: walking without looking at one's feet, typing without looking at one's hands, or moving limbs with one's eyes closed.

Vestibular sense

-fluid filled canals and a pair of calcium crystal filled
vesibular sacs located in the ears monitors the heads and bodys movement
-exp: riding a skateboard, sitting up straight

Synesthesia

Some synesthetes hear, smell, taste or feel pain in color