Unit 1 Study Cards (outer ear) Flashcards
Pinna (Outer Ear Anatomy)
AKA Auricle
Outer ear portion and what we refer to as “the ear.”
Skin covered cartilage connected by ligaments with vestigial intrinsic muscles
“Lobule” or “ear lobe” has NO CARTILAGE
Helps us determine whether a sound source is directly in front of or directly behind us.
External Auditory Canal (Outer Ear Anatomy)
Terminates at the tympanic membrane which separates the outer ear from the middle ear.
Main RESONANCE/AMPLIFICATION area: amplifies frequencies from 2000 to 5000 Hz in adults.
more horizontal in children due to developing skull
Outer 1/3 is Cartilaginous portion has thick skin containing hair cells that create cerumen.
Inner 2/3 is the the osseous or bony portion of canal (no cerumen or hair)
External Auditory Meatus (Outer Ear Anatomy)
This is the opening of the external auditory canal
Concha (Outer Ear Anatomy)
The Deepest Groove in the Pinna (a bowl-shaped depression) leading right to the opening of the ear canal.
Tympanic Membrane
AKA the ear drum.
It separates the outer ear from the middle ear.
Cone shaped with the tip pulled about 2mm toward the middle ear. CONCAVE
Receives sound waves and transmits them to the middle ear ossicles.
Thin, pearly grey, translucent, highly elastic structure (angle of membrane is different in right - 1 o’clock vs left ear - 11 o’clock).
Outer Ear Functions (There are 3)
Amplification
Localization
Protection
Outer Ear Mode of Operation
Air Vibration (sound)
Amplification Function
Resonation serves as a major enhancer for speech sounds
CONCHA - 5kHz resonance
EXTERNALM AUDITORY CANAL - 2.5 kHz resonance
Localization Function
Localization is the process of determining the location of a sound source in space and it includes TWO COMPONENTS:
1. Azimuth Estimation - angle direction on horizontal plane (involves differentiation between between front, right, back, and intermediate directions)
2. Elevation Estimation - angle direction on a vertical plane (involves differentiation between sounds coming from various angles above and below the listeners ears.
confusions supplemented by front back cues from Pinna
Protection Function
LENGTH of External Auditory Canal protects the tympanic membrane and the middle ear mechanism from physical damage and abuse.
MIGRATION OF CERUMEN out of the ear along with dirt and deebris
Monaural Localization Cues
Cues created by the reflection and refraction of sound by the folds, cavities, and ridges of each outer ear.
(primary cues for localization of sound sources in the vertical plane).
Binaural Localization Cues
cues created by differences between sounds arriving at the right ear and the left ear.
(primary cues for localization of sound sources in the horizontal plane).
*Binaural localization cues are interaural (between ears) differences in intensity and phase (arrival time) of sounds arriving at the left ear and the right ear.
ITD (Interaural Time Difference)
differences in time between two ears
sound arriving from the left side will arrive earlier than on the right and vice versa
LOW FREQUENCY CUE (frequency < head size)
IID (Interaural Intensity Difference)
differences in intensity between two ears
sound arriving from the left side will be louder than sound arriving at the right side and vice versa
HIGH FREQUENCY CUE (frequency > head size)
HRTF
Head Related Transfer Function is the direction and frequency dependent ratio of the sound pressure arriving at the ear of a listener to the sound pressure that would exist at this location if the listener was not present.
