Part Three - The Ear Flashcards
What are the two vital functions of the ear?
To mediate the sense of hearing and the sense of balance.
What are the three sections of the ear?
Inner ear, middle ear, outer ear.
What does the outer ear consist of?
Flap of cartilage which terminates at the eardrum.
What do the wax-producing cells in the eardrum do?
Prevent intrusions from reaching the eardrum. Insects, dust and even hot and cold temperatures.
What does the middle ear consist of?
Starts at the eardrum and goes to the oval window (connecting to the cochlear). Includes hammer, anvil and stirrup as well as the oval window.
How do sound waves reach the brain as sound we can hear?
Eardrum vibrates sound waves to the hammer, anvil and stirrup. These bones then amplify and conduct those vibrations to the cochlea. The stirrup connects to the cochlea at the oval window and it is from there that the mechanical energy of vibration begins its conversion to electrical energy of nerve impulses which are carried to the brain via the cochlea nerve.
What does the inner ear consist of?
Cochlear and semicircular canals.
How does the cochlear work?
Filled with a fluid called endolymph which contains tiny hair-like cells. Vibrations set up pressure waves which travel through the fluid which subsequently responds to the pressure waves and generate nerve impulses. The brain then interprets this as sound.
How does the vestibular system work?
Semicircular canals are three hollow loops located at the top of the cochlea which sense angular acceleration. They are filled with endolymph and contain tiny hair-like cells called cupula. As head or body changes its speed or attitude, the fluid washes over the hairlike cells which respond by sending nerve impulses to the brain.
Cupula respond to the initial change. A prolonged movement will be eventually be perceived as no movement.
Otolith organ consists of the utricle which lies horizontally and detects horizontal accelerations and the saccule which lies vertical and detects vertical accelerations.
What are the three information sources used in maintaining balance?
Ears, eyes, postural.
What is frequency measured in?
Hertz - vibrations per second.
What is the frequency range of intelligible speech?
300 - 5000 Hz
What is the intensity of volume measured in?
Decibels.
What is the sound intensity between 30 and 40 dB?
10x louder.
Above what dB does sound produce discomfort?
80 dB
