1. AIM: How do we hear?

2. Opponent Process Theory Hering proposed that we process four primary colors combined in pairs of red-green, blue- yellow, and black-white. Cones Retinal Ganglion Cells

3. Color Constancy Color of an object remains the same under different illuminations When context changes, the color of an object may look different. R. Beau Lotto at University College, London

4. Audition

5. http://www.freemosquitoringtones.o rg/

6. AIM: How do we hear?

7. Hearing Range 40 Hz to 60,000 Hz – Dog’s 20 Hz and 120,000 Hz – Bat’s 20 to 20,000 Hz –Human’s (Human voice range- 85- 255 Hz)

8. The Stimulus Input: Sound Waves Sound waves result from the compression of air molecules. Acoustical transduction: Conversion of sound waves into neural impulses in the hair cells of the inner ear.

9. Sound Characteristics 1.Frequency (pitch) 2.Intensity (loudness) 3.Quality (timbre)

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

11. Intensity (Loudness) Intensity (Loudness): the amplitude, relates to the perceived loudness.

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

13. Quality (Timbre) Quality (Timbre): Characteristics of sound from a zither and a guitar allows the ear to distinguish between the two. http://www.1christian.net www.jamesjonesinstruments.com Zither Guitar http://www.youtube.com/watch?v=p1FlDdNLkD4 http://www.youtube.com/watch?v=C9ZRS0F5t34

14. Overtones Overtones: Makes the distinction among musical instruments possible.

15. The Ear Dr. Fred Hossler/ Visuals Unlimited

16. The Ear Outer Ear: Pinna. Collects sounds. Middle Ear: Chamber between eardrum and cochlea containing three ossicle bones (hammer, anvil, stirrup) Inner Ear: Innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.

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

18. Theories of Audition Place Theory -Herman von Helmholtz -suggests that sound frequencies stimulate the basilar membrane at specific places resulting in perceived pitch. http://www.pc.rhul.ac.uk

19. 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. Sound Frequency Auditory Nerve Action Potentials 100 Hz 200 Hz

20. Frequency Theory: Volley Firing Alternated neural firing can achieve frequencies above 1000 Hz per second

21. Localization of Sounds Because we have two ears, sounds that reach one ear faster than the other ear cause us to localize the sound.

22. Localization of Sound 1. Intensity differences 2. Time differences Biaural Cues: Time differences as small as 1/100,000 of a second can cause us to localize sound.

23. Hearing Loss Conduction Hearing Loss: Hearing loss caused by damage to the mechanical system Sensorineural Hearing Loss (nerve deafness): Hearing loss caused by damage to the cochlea’s receptor cells or nerves

24. Hearing Deficits Older people tend to hear low frequencies well but suffer hearing loss when listening for high frequencies.

25. Deaf Culture Cochlear implants are electronic devices that enable the brain to hear sounds. Cochlear ImplantDeaf Musician EG Images/ J.S. Wilson © Wolfgang Gstottner. (2004) American Scientist, Vol. 92, Number 5. (p. 437)