4The Stimulus Input: Sound Waves Sound waves are compressing and expanding air moleculesFrequency:The number of complete wavelengths that pass a point in a given time (for example, per second)Pitch:A tone’s experienced highness or lowness
5The Stimulus Input: Sound Waves Amplitude:The height of a sound waveMeasures the energy/intensity of the waveLoudnessMeasured in decibels
10Perceiving Pitch Place Theory: Frequency Theory: Links the pitch we hear with the place where the cochlea’s membrane is stimulatedDifferent frequencies vibrate in different places of the cochleaProblem: low-pitched sounds not localizedFrequency Theory:The rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, enabling us to sense its pitchThe entire cochlea is believed to vibrate at a particular frequencyProblem: high-pitched sounds (1,000 waves/second) travel faster than neurons
11Locating SoundsBecause we have two ears, sounds that reach one ear faster than the other ear cause us to localize the sound.
12Locating SoundsWhy is it difficult to locate a sound when it occurs directly ahead, behind, overhead, or beneath us?It is easier to locate a sound when it comes from either side of us; for this reason, to pinpoint a sound, we often need to cock our head, allowing each ear to receive a slightly different message.
13Hearing Loss and Deaf Culture Conduction Hearing Loss:Caused by damage to the mechanical system that conducts sound waves to the cochleaE.g. punctured eardrumSensorineural Hearing Loss:Caused by damage to the cochlea’s receptor cells or to the auditory nerves“Nerve Deafness”Biological changes associated with heredity, aging, and prolonged exposure to ear-splitting noise or music
14Hearing Loss and Deaf Culture Cochlear Implant:A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea
15Hearing Loss and Deaf Culture What are the benefits and limitations of using sign language exclusively in a hearing world?What should the hearing world’s response be to the use of sign language?
16Review What is determined by the frequency of a sound? The amplitude? Discuss the path in which sound travels between entering the ear and reaching the brain.How do we locate sounds?What is the difference between Conduction and Sensorineural Hearing Loss?
17Homework Unit 4 FRQ Unit 4 Quiz: “Sensation and Perception” Unit 4 Test: “Sensation and Perception”Chapter 5 Outline: “States of Consciousness”