Chapter 9 Hearing and Language Pages 270 excluding language All of chapter 10 323 Windows on the Outside World Hearing and language ch 9 Vision ch 10 Body senses motor control ch 11 Hearing and vision are newer on the evolutionary timeline advantage in proximity Stronger selectional pressure for long distance perception Chemical senses like taste smell and touch are older on the evolutionary timeline Similarities Acquiring info on the outside world through the senses Joined directly to response reflex Processing sensory info Taken care of by interneurons CNS What you see is a perceptual model of the world created by the brain should be accurate so you can adapt to environment know it s a model because illusions can occur Acting upon the world communication movement It s a cycle see arrows Basic Concepts Sensory system set of components of the PNS and CNS involved in acquiring and processing of specific sensory info e g auditory info Sensation acquisition of sensory info Perception interpretation of sensory info Receptor a cell that is suited by its structure and function to respond to a specific form of energy e g sound Often it is a specialized neuron look at eye nose even ear neurons look like sensory neurons that transformed over time to be specialized Transducer device that converts energy from one form to another e g photoelectric cell receptors are biological transducers Stimulus specific energy form for which the receptor is specialized e g vibration for hair cells in inner ear Stimulus vibration kinetic energy in a conducting elastic medium normally air what we call sound Sequence of pressure changes of atmosphere alternating pressure changes compression decompression can think of it as waves HORIZONTAL waves slinky Hearing Types of Sounds Physical energy Pure tones single frequency Frequency of waves of compression and decompression cycles that occur per unit of time Single frequency looks like the wave drawn above typical picture Complex sounds combination of 2 frequencies Produce more pure tones at the same time Experience of Sound Part of the model of the world we create for ourselves Pitch experience of the frequency of a sound Loudness experience of the intensity or amplitude of the wave i e physical energy of a sound The physical characteristics frequency and amplitude are independent but our perception of them is not we hear higher pitches as louder more adapted to hear higher because we tend to speak in those pitches Auditory Apparatus Outer ear Middle ear Inner ear Cochlea Pinna literally means fin in latin doesn t really do a lot of funneling as you would think External auditory canal amplifies waves Tympanic membrane eardrum waves cause it to vibrate Ossicles tiny little bone in Latin transfer amplify vibrations from eardrum to oval window in cochlea Hammer Anvil Stirrup like levers Forms gills in fish Cochlea land snail in Latin receptors found here transduction from kinetic to something the receptors can understand Semicircular canals Basilar membrane separates cochlea in half Vestibular and Tympanic canals Fluid inside Stirrup makes physical contact with cochlea with the oval window flexible membrane Causing vibrations to transfer to fluid and then to the basilar membrane Round window another opening also covered in elastic membrane which discharges the kinetic energy from the waves allows waves to be transferred at all i e can t squeeze a completely full water bottle without give somewhere How kinetic is transformed into signal nerves can read neurotransmitter or electrical signals Organ of Corti Inner hair cells 1 row about 3 400 per ear tend to act more as receptors 3 rows of outer hair cells about 12 000 per ear tend to act more as muscles rather than receptors Hair cells will move in response to vibrations cilia will bend in one direction or another depending on shearing motion of hair cells transduction kinetic energy to neurotransmitter The transduced information then travels along the fiber of the auditory nerve to the brain where we become aware of hearing something Auditory Pathways and Cortex picture in textbook Input from auditory nerve Cochlear nucleus Medulla called this because it s the first brain station to receive info from cochlea Superior olive Medulla called this because looks like an olive and it s above the other structure that also looks like an olive important in knowing where a sound came from Inferior colliculus Midbrain tectum also involved in location of sound source and connection with response systems Medial Geniculate nucleus of thalamus Forebrain Primary auditory cortex Forebrain