Audition (hearing) What are the characteristics of air pressure waves that we hear? How does the ear transform sound energy into neural messages? What Theories Help us understand pitch perception? How do we locate sounds? What are common causes of hearing loss, and why does controversy surround cochlear implants?
What are characteristics of air pressure waves that we hear as sound? Amplitude – the strength of sound waves Frequency- number of wavelengths that pass through a certain point over a given time. This determines pitch.
Hair Cells in the Cochlea Most hearing loss is caused by damage to these hair cells. Think about a thick carpet. When you stand on it for a few moments and move, the dented carpet slowly comes back to its original form. However, move a table or TV stand that has been in the same place for a lone time, and the carpet is permanently deformed. Also, think of bed head!
How is loudness perceived? Not by how much the hair cells in the cochlea “sway”, but the number of hair cells swaying determine loudness.
3. What theories help us understand pitch perception? • Place Theory – created by Hermann von Helmholtz, says that we hear different pitches because different sound waves affect different parts of the cochlea. • Frequency Theory – belief that the rate of a nerve impulse traveling on the auditory nerve moves as fast as the frequency of a tone. Thus, we sense its pitch.
How do we locate sound? Having two ears is the key. • Because they are separated, a noise on our left side is heard by the left ear sooner. • The pitch of the sound in the left ear will also be more intense.
What are the common causes of hearing loss, and why does controversy surround cochlear implants? Answer this in your notebook for homework?