The auditory system allows humans to perceive sound. Sound waves enter the outer ear and vibrate the eardrum, transmitting vibrations through three small bones to fluid in the inner ear. Hair cells in the cochlea convert vibrations into nerve signals about sound frequencies and intensities. The brain processes these signals to perceive qualities like pitch and loudness. Damage to hair cells or nerves can cause hearing loss while cortical damage may impact speech understanding.

1. The Auditory System

3. Properties of Waves

6. A Diagrammatic Representation

8. Divisions of the Ear

13. Picturing the Ossicles

16. The Middle & Inner Ear

18. Picturing the Cochlea

20. A Single Turn

22. Picturing Frequency Processing

25. Picturing the Organ of Corti

32. Picturing Hair Cell Movement

56. A Variant Scale Illusion When listening to this pattern through loudspeakers, notice that when each channel is played separately, it appears to shift dramatically in pitch, but when both channels are played together, two smooth melodies are heard. The brain creates order out of chaos.