Hearing Flashcards
Explain sound waves and how pitch, loudness and tonal quality effect them Describe the anatomy of the ear Explain how we are sensitive to different frequencies Explain how we are sensitive to sound loudness and location Explain how the organ of corti generates APs Describe some different types of deafness
What is sound?
Sound is transmitted through disturbance in the air
How does the human ear hear?
It detects these small changes in pressure using mechanoreceptors: 20Hz - 20kHz
What is the Doppler effect?
The Doppler effect is caused by sound waves being affected by relative motion
What happens as a car moves towards you?
The sound waves are compressed, increasing the pitch
What happens as a car moves away from you?
The sound waves are stretched, lowering the pitch
What are 5 parts of the outer ear?
Cartilage - the ear Pinna - ear lobe External auditory meatus - air tunnel Temporal bone Tympanic membrane - ear drum
What are the 3 bones in the middle ear?
Malleus - hammer
Incus - anvil
Stapes - stirrup
What are the 2 muscles in the middle ear?
Tensor tympani
Stapedius
Contract to prevent damage by loud noise
What is the pressure equaliser called between outer and middle ear?
Eustachian tube
What does the oval window do?
Projects into the top section of the vestibular tube duct
What are the 4 parts of the inner ear?
Semicircular canals - sense equilibrium
Vestibulo-cochlear nerve
Cochlea - mechanoreceptors
Round window
What are the 3 chambers of the inner ear?
Scala vestiboli - vestibular membrane
Scala media - organ of corti
Scala tympani - basilar membrane
High frequency does not get far but low frequency does
How is pitch determined in the ear?
By which hair cells are affected
How is loudness measured in the ear?
Loudness is proportional to frequency of action potentials in hair cells
How is sound location measured by the ears?
Time difference in reaching 2 ears (low pitch) and difference in intensity (high pitch)
What is the organ of corti?
It is made up of the vestibular membrane, basilar membrane and tectorial membrane. It has multiple hair cells which detect sound and translate it to the brain
How do hair cells in the ear cause APs? (mechantransduction) (8)
Fluid vibrates Hairs bend K+ influx from endolymph Cell depolarisation Receptor potential VG Ca2+ channel opens Neurotransmitter released APs in afferent auditory nerve
How does auditory information get to the primary auditory cortex?
Via the thalamus
How can hearing loss occur?
Damage to unilateral A1
How can cortical deafness occur?
Bilateral A1
What are the 3 major types of deafness?
Conduction deafness - outer/middle
Nerve deafness - hair cells/inner ear
Cortical deafness - auditory cortex
What is conduction deafness and what causes it? (3)
Impaired transmission in the outer/middle ear
Wax, ossicle degeneration and thickened tympanic membrane contribute to this
What is nerve deafness and what causes it (5)?
Damage to hair cells or nerves in the inner ear Continuous loud noise Drugs Antibiotics Diuretics Genetics
What is cortical deafness and what causes it? (2)
Damage to auditory cortex
TBI, stroke
What is tinnitus and what causes it? (5)
Sounds heard when no sound is present (ringing) Damaged hair cells Brain tumours TBI Ear infections Noise-induced hearing loss
What is amplitude?
Louder sound = higher amplitude of sound wave
What is pitch?
Increased frequency of sound wave shows higher pitch
What is tonal quality?
regularity in sound waves
