PSYC 110 Lecture Notes - Lecture 14: Piccolo, Basilar Membrane, Auditory Masking
27 Jun 2018
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Our world is limited to the sensory neurons we have and their range
Stroboscope goes through the nose to look at the vocal cords -> lower on the low notes and stretching
out on the high notes, only takes moving air back and forth at different frequencies
Physical Stimulus (the air) -> Physiological response (transduction of air by the hair cells in the cochlea
which moves up in our brain) -> sensory experience (song being sang and heard)
Sound is the vibration of air or some other medium produced by an object. The vibration moves in a
wave.
Frequency - Length of the soundwave (rate at which molecules move back and forth) , peak to peak how
far apart is the distance. Low sound frequency is a low pitch and the peaks are far apart. High frequency
is high pitched and the peaks are closer. Measured in Hz, ferrets, dolphins can hear on a higher
frequency than humans.
Amplitude - Intensity of sound wave (total pressure exerted by molecules of air as they move back and
forth), peak are shorter or taller in height. High amplitude has higher peaks and causes loud sounds, Low
amplitude has shorter peaks and causes softer sounds - measured by decibel level. Rock band is
dangerous zone. Anything above 85 db over prolonged periods can produce hearing loss
Pure tone -> constant frequency sound wave, looks like a sine wave - very difficult to produce.
Bats have the keenest hearing. In complete darkness, they can fly around obstacles to escape. They
navigate with the help of sonar, or reflected sound waves. They send out high-pitched chirps, above the
frequency range of humans, and analyze the echoes to find out the size, shape, characteristic, direction
of movement of a target insect.
Hearing helps us to detect and respond to potentially dangerous situations that can occur in the dark, or
anywhere out of view. Used to identify animals and also for interpreting language and dialogue.
Sound refers to both, a type of physical stimulus and to the sensation produced by the stimulus. A tree
falling makes a sound regardless of whether anybody is there to hear it.
Hearing is sensitivity to pressure on a special sensory tissue in the ear. Moths sense sounds through a
touch receptor on their skin that detects sound waves. Humans had the same but this spot on the skin
migrated to an area in the brain, and special organs like ears originated.
The Ear:
Outer Ear - Sound waves are collected. Has the pinna (pinpoint the location of the sound, localize things)
and the vibrations travel through the outer ear and go through the auditory canal and hit the structure
called tympanic membrane (eardrum, super painful when ruptured, very sensitive, has a thin
membrane) which vibrates too
Middle ear - Sound waves are amplified. Back side of eardrum is ossciles (hammer, anvil, stirrup) that
are tiny bones that pick the vibrations and amplifies it and attaches to the oval window where the
stirrup will push on the oval window and move fluid back and forth into the cochlea in the inner ear -
main function is to increase pressure exerted by sound waves on inner ear for transduction to occur
Inner ear - Sound waves are transduced into coded neural messages. Really bad ear infection or balance
problems is an inner ear problem, fluid filled channels that help maintain balance by orienting the brain
(semicircular canals). The channels that let the fluid flow around can get blocked -> patient lays on the
ground and moves the head in different directions to unblock the ears. Motion sickness -> moving a lot,
your semicircular canals detect that and when you're reading or studying, your visual system says you're
not moving but your semicircular thinks you're moving and this mismatch gives you a headache. Sound
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Document Summary
Our world is limited to the sensory neurons we have and their range. Stroboscope goes through the nose to look at the vocal cords -> lower on the low notes and stretching out on the high notes, only takes moving air back and forth at different frequencies. Physical stimulus (the air) -> physiological response (transduction of air by the hair cells in the cochlea which moves up in our brain) -> sensory experience (song being sang and heard) Sound is the vibration of air or some other medium produced by an object. Frequency - length of the soundwave (rate at which molecules move back and forth) , peak to peak how far apart is the distance. Low sound frequency is a low pitch and the peaks are far apart. High frequency is high pitched and the peaks are closer. Measured in hz, ferrets, dolphins can hear on a higher frequency than humans.
