1. Audition (Hearing) The Stimulus Input: Sound Waves The Ear Hearing Loss and Deaf Culture

2. The Stimulus Input: Sound Waves
Sound waves are composed of compression and expansion of air molecules.
OBJECTIVE 11| Describe the pressure waves we experience as sound.

3. Sound Characteristics
Wavelength or Frequency (pitch)
Amplitude or Intensity (loudness)

4. Frequency (Pitch)
Frequency (pitch): The dimension of frequency determined by the wavelength of sound.
Wavelength: The distance from the peak of one wave to the peak of the next.

5. Intensity (Loudness)
Intensity or (Loudness): Amount of energy in a wave, determined by the amplitude, relates to the perceived loudness.

6. Loudness of Sound
Richard Kaylin/ Stone/ Getty Images
120dB
70dB

7. The Ear
Dr. Fred Hossler/ Visuals Unlimited
OBJECTIVE 12| Describe the three regions of the ear, and outline the series of events that triggers the electrical impulses sent to the brain.

8. The Ear Outer Ear: Pinna-Collects sound waves.
Auditory Canal- channels sound waves toward ear drum
Eardrum- tight membrane that vibrates with the waves

9. The Ear
Middle Ear: Chamber between eardrum and cochlea containing three tiny bones that concentrate the vibrations of the eardrum on the cochlea’s oval window.
hammer (Malleus)
anvil (Incus)
stirrup (Stapes)

10. The Ear Inner Ear: Innermost part of the ear.
Cochlea – incoming vibrations on the oval window (membrane) cause the fluid that fills the snail-shaped tube to be jostled.
Basilar Membrane- lined by hair cells/ cilia that ripple with the motion. The movement of the hair cells triggers an impulse for adjacent nerve cells.
Auditory Nerve- the nerve cells that converge to send messages to the thalamus and on to the auditory cortex.

11. Cochlea
Cochlea: Coiled, bony, fluid-filled tube in the inner ear that transforms sound vibrations to auditory signals.

12. Theories of Audition
Place Theory suggests that sound frequencies stimulate the basilar membrane at specific places resulting in perceived pitch.
OBJECTIVE 13| Contrast place and frequency theories, and explain how they help us to understand pitch perception.

13. Theories of Audition
Frequency Theory states that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.
Auditory Nerve
Action Potentials
Sound
Frequency
200 Hz
100 Hz

14. Localization of Sounds
Because we have two ears, sounds that reach one ear faster than the other ear cause us to localize the sound.
OBJECTIVE 14| Describe how we pinpoint sounds.

15. 1. Intensity differences
Localization of Sound
1. Intensity differences
2. Time differences
Time differences as small as 1/100,000 of a second can cause us to localize sound. The head acts as a “shadow” or partial sound barrier.

16. Hearing Loss
Conduction Hearing Loss: Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.
Sensorineural Hearing Loss: Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve, also called nerve deafness.
OBJECTIVE 15| Contrast two types of hearing loss, and describe some of their causes.

17. Deaf Culture
Cochlear implants are electronic devices that enable the brain to hear sounds.
OBJECTIVE 16| Describe how cochlear implants function, and explain why Deaf culture advocates object to these devices. Where these implants are pertinent for hearing parents with deaf children, deaf culture advocate not using them especially on children deafened before learning to speak.
Wolfgang Gstottner. (2004) American
Scientist, Vol. 92, Number 5. (p. 437)
EG Images/ J.S. Wilson ©
Deaf Musician
Cochlear Implant