Flashcards in Module D-11 Deck (65)
What is sound?
pressure waves generated by mechanical vibrations
what are 3 characteristics of sound?
1) Frequency - perceived as a high or low tone or pitch
2) Intensity or amplitude- perceive as loudness
3) the point of origin - location
What is unit for the frequency of sound?
cycles per second ( cps) or Hertz ( Hz)
What is frequency range of sound audible to humans?
20 to about 20,000 Hz
What is sound intensity?
sound pressure levels (p) relative to the human auditory
threshold (p0) at 1000 Hz
Equation for sound intensity
Intensity (dB) = 20 log (p/p0)
unit for sound intensity
What is the speed sound travels through air?
331 meter per second (m/s)
Describe pathway of sound into outer ear
The outer ear, filled with air, focuses sound into the external auditory meatus. Pressure waves generated by sound pass through the external auditory meatus
and produce vibrations of the tympanic membrane.
What separates the inner and outer ear?
What is the middle ear filled with?
How is the middle ear connected with the nasopharynx?
Eustachian ( pharyngotympanic ) tube
What are the ossicles of the ear?
malleus, incus and stapes
What are the 2 muscles of the inner ear?
m. tensor tympani and the m. stapedius
What is the function of the 2 muscles of the inner ear?
Contract To prevent damage to the inner ear during high intensity sound
The stapes vibrates the _______ window to produce vibratory waves of the inner ear
What is the bony compartment that contains the inner ear?
Which compartments of the inner ear contain Perilymph?
scala vestibuli and scala tympani
Which compartments of the inner ear contain Endolymph?
The hair cells are located in the ___________ of the chochlea
Organ of corti
Where are the cell bodies of the afferents that receive the signal from the hair cells?
Spiral ganglion (form axons of auditory nerve CN VIII)
What are the 2 mechanisms of sound amplification in the middle ear?
1) Size difference of Tympanic membrane compared to oval window
2)Lever Ratio of the Ossicular Chain
How does the size difference cause pressure amplification of sound?
because the smaller the surface area the greater the pressure produced for the same force
How does the lever ratio of the ossicular chain cause pressure amplification?
Large movements (with little force) of the tympanic membrane are transformed into little movements (with greater force) at the oval window
By how much does the middle ear amplify pressure?
Which ossicle is the tensor tympani muscle attached to ?
Which ossicle is the stapedius muscle attached to ?
Which nerve innervates the tensor tympani muscle?
Trigeminal nerve V
Which nerve innervates the Stapedius muscle?
Facial nerve VII