The document summarizes the physiology of hearing. It describes how sound is transmitted through the ear as a pressure wave and perceived as sound information. It details the anatomy of the outer, middle and inner ear. It explains how sound waves cause vibrations that are amplified and transmitted through the ossicles to the cochlea fluid. Within the cochlea, vibrations travel in a wave along the basilar membrane to stimulate hair cells, which transmit signals to the auditory nerve.

1. Physiology of Hearing Prof. Vajira Weerasinghe Dept of Physiology

3. Compression the graph showing a sine wave refers only to variations in pressure or compression, not to the actual displacement of air Sound waves Compression Compression Rarefaction Rarefaction Rarefaction

5. Properties of sound Wavelength Refers to the physical distance between successive compressions and is thus dependant on the speed of sound in the medium divided by its frequency Amplitude (Intensity or loudness) Refers to the difference between maximum and minimum pressure Frequency (pitch) Refers to the number of peak-to-peak fluctuations in pressure that pass a particular point in space in one second Velocity Refers to the speed of travel of the sound wave. This varies between mediums and is also dependant on temperature (in air at 20°C it is 343 m/s)

11. Parts of the ear

16. Cross section through cochlea

19. Cohlea

21. Organ of Corti

24. Hair cells

34. From the ear to the auditory cortex

44. Cochlear implants