1. External ear functions
Modifies the spectrum of incoming sounds.
Resonance of external auditory meatus
Head related transfer functions
Protection to middle and inner ear structures

2. Resonance of ear canal Resonance of ear canal: Around 2.5 kHz
Resonance of the concha: Around 5 kHz
Net effect: Boost in frequency region between 1.7 and 7 kHz

4. External ear functions
Modifies the spectrum of incoming sounds.
Resonance of external auditory meatus
Head related transfer functions
Protection to middle and inner ear structures

5. Head-related transfer functions
Inter-aural amplitude/level difference
Inter-aural time difference
Important for sound localization