3. EXTERNAL EAR
Pinna and Concha
• Gather sound energy
• provides cue about the elevation of sound source (due to selective
frequency)
Auditory meatus
• Boost the sound pressure (30 -100 times) for 3KHz frequency – resonance
effect
( makes sensitive to hearing loss in 2-5KHz – explosion , heavy machinery
sound)
4. MIDDLE EAR
• Amplification by ear ossicles
By two mechanical process
1. by focusing the force from
large area to small area
2. mechanical advantage gained
by lever action of ossicles
Tensor tympani (CN V) and
Stapedius (CN VII) – protect inner ear