Week of Notes (3-29-16)
Week of Notes (3-29-16) PSYCH 3240
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This 3 page Class Notes was uploaded by Lucy Stevens on Friday April 1, 2016. The Class Notes belongs to PSYCH 3240 at Clemson University taught by Dr. Claudio Cantalupo in Spring 2016. Since its upload, it has received 20 views. For similar materials see PSYCH 3240 in Psychlogy at Clemson University.
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Date Created: 04/01/16
Chapter 9 Continued (3-29-16) Read up to page 321 *Pitch Perception: basilar membrane vibrates in synchrony with a sound frequencyè auditory nerve axons fire at the same frequency o Problem: individual neurons can fire at no more than about 1000 Hz, but we can hear up to 16,000+ Hz. o Volley Theory: groups of neurons can follow the frequency of a sound where a single neuron cannot; can even explain all of our voluntary sound perception o Place Theory: sounds with different frequencies induce peaks of maximal vibration in different places on the basilar membrane (basilar membrane location matters); postulates a comparison of what frequency is coming in (high or low) and what place the basilar membrane vibrates • Apex (of basilar membrane) is wide and floppy • Base (of basilar membrane) is narrow and stiff • Low frequency: cause maximum vibrations near the apex • High frequency: cause maximum vibrations near the base • We can think of the basilar membrane as a map of frequencies; as the frequency gets lower and lower it travels towards the apex. • Tonotopic Organization of the Basilar Membrane • Problem with Place Theory: with sounds below 200 Hz the whole basilar membrane vibrates equally- i.e., no peaks of vibration o Primary Auditory Cortex: Contains a tonotopic map of the basilar membrane o There is an orderly system of the tones *Pitch Perception 1. Frequency Theory 2. Place Theory Combine to form the Frequency-Place Theory *Frequency-Place Theory • Synchrony of firing rate of auditory nerve axons with sound frequencyè pitch perception of sounds up to about 200 Hz. • Place of maximal vibration on basilar membraneè pitch perception of sounds greater than 200 Hz. • Able to hear pure tones (made of one frequency), which are not very common in nature; most of our auditory experience is not pure tones Perception of complex sounds: *Fourier (Harmonic) Analysis • Any complex sound can be broken down into pure tones also known as component frequencies • Frequency Fundamentals: • Overtones: • The basilar membrane of the cochlea acts as the Fourier/Harmonic Analysis • Major role is played by the peripheral structure *Cocktail Party Effect • Ability to filter out meaningful auditory signals from a complex background system • Like you’re listening to a symphonic orchestra concert and all the sounds are coming to your ear. You are able to filter everything out except maybe what just the violin is playing. Amazing ability to do this. Physically, the sound that gets to your ear is not separated from the different instruments. • Attention is involved • Possible role played by outer hair cells (found on the basilar membrane) • Outer hair cells actually mute some certain areas of the basilar membrane, which is how the cocktail effect works. Its like when you put your finger on the skin part of a drum and you hit the drum and no sound happens. *Sound Localization • It is important to be able to hear sounds, but it is equally important to know where that sound is coming from. • Binaural Cues: involve use of both ears; bran locates the source of a sound based on differences between the sound at two ears; three types 1. Phase Difference: a sound arriving from one side of the body is at a different phase of the wave at each ear (works for low- frequency sounds) a. Dog Head Cocking: response to auditory stimulation; behavioral way of being better able to perceive the sound Resources Garrett, Bob. Brain & Behavior: An Introduction to Biological Psychology. Vol. 3. Thousand Oaks: SAGE Publications, 2010. Print. Cantalupo, Ph.D., Claudio. "PSYCH 3240." Psych 3240 Lecture. 120 Brackett Hall, Clemson. 22 Mar. 2016. Lecture.