These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Outline of Last Lecture: 1. Cognitive Development Outline of Today’s Lecture: 1. Auditory Sensation 2. Ear anatomy 3. Auditory path to the brain 4. Perception Today’s Lecture: 1. Auditory Sensation a. Sound is caused or created by compression of air – can be translated to a sequence of frequencies of pressure waves b. Frequency – how often per second – leads to pitch c. Amplitude – Intensity – leads to loudness 2. Ear anatomy a. b. Cochlea – coiled up, has fluid inside i. Basilar membrane in the middle of the cochlea (vibrates in response to sound) NSCS 200 Richard Levine Spring 2013 Week 7 Lecture 11 February 19ii. iii. Hair cells in each region along the basilar membrane are excited maximally by different frequencies of sound iv. v. Organ of Corti – sits within the cochlea, the outside fluid (endolymph) has a large [K+] 1. Has many hair cells (stereocillia); move back and forth as sound waves come in 2. Is in contact with the tectorial membrane which acts as a plastic wrap 3. Since there is a high [K+] outside the organ of corti inside the endoplymph, when the stereocillia move in specific ways it opens the K+ channels (mechanosensory channel) 4. Opening the mechanosensory channel allows K+ to move into the cell, causing depolarization 5. This excites sensory neurons of the spiral ganglion, which sends action potentials down the auditory nerve 6. Sensory neurons are “tuned” to specific frequencies a. Cells will respond better to frequencies they are specifically tuned to 3. Getting into the braina. b. Localizationi. ii. Coincidence detectors are fed stimulus from delay line axons 1. The coincidence detector that gets both signals at the same time can “triangulate” the position of the sound in space 4. Perception a. Why do we have sensory systems? To monitor the environment. b. We can react to the presence of light waves, sound waves, odors, taste, or touch c. Tonotonic maps – maps preferential frequencies for the cochlea (low frequencies in the center, high frequencies on the outside)d. e. Complex tones – comprised of pure tones and harmonic tones f. Timbre – purity level of a sound; how are harmonics incorporated in a sound; this is what allows the same note sound differently if played by different instruments g. Language – special case of auditory objects in the form of morphemes, words, and sentences i. There is great variability in humans because we can understand and recognize words that are spoken differently by different
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