Physiology of Hearing Flashcards
What are sound waves?
They are audible variations in air pressure (compression and rarefaction).
Do air molecules travel directly from the source of sound to your ear?
NO they do not
Each individual air molecule only moves a small distance as it vibrates, but it causes the adjacent molecules to vibrate in a rippling effect all the way to the ear.
What does the wavelength and amplitude of a sound wave
The pressure of the sound
How much the particles are being moved
Define sound intensity
the sound power per unit area (power = amplitude^2).
What are the basic units of sound intensity?
watts/m2 or watts/cm2
BUT more in normal life we use
decibels (dB)
What is sound intensity in lay man terms?
How loud the sound is
What is the threshold for hearing in dB?
= 0 dB
What is the sound intensity of vacuum cleaner?
= 80 dB
Define frequency
Frequency is the speed of complete back and forth vibration
In what unit so we measure frequency?
Hertz
What is the frequency range humans can hear at?
20-20,000 Hz
What does 1 Hz equal?
1 Hertz = 1 vibration/second
What is the frequency (pitch) of spoken words?
2000-4000 Hz
What is the speed of sound?
343 m/sec
What is ear split into?
3 sections:
Outer ear
Middle ear
Inner ear
What makes up the outer ear?
The pinna and the auditory canal
What makes up the middle ear?
Ossiclles and the tympanic membrane
What makes up the inner ear?
The oval window and cochlea
What are the outer and middle ear full of?
Air
What is the inner ear filled of?
It is fluid filled
What does the pinna act like?
Acts like a funnel to collect sound waves
What does the auditory canal do?
focuses the sound waves to increase the pressure on the tympanic membrane in a frequency sensitive manner.
What does the design of the pinna help us to do?
Helps us to determine sound localisation.
What is conductive hearing loss?
A clinical condition where your outer ear may be damaged
Where does the middle ear stem from and to?
Spans from the tympanic membrane to the oval window on cochlea
Describe the middle ear?
It is an air filed cavity
Name the 3 smallest bones in the body
- Malleus (hammer)
- Incus (anvil)
- Stapes (stirrup)
What is the role of the middle ear?
Converts wave in air to fluid
What does the conversion of waves in air to fluid result in?
leads to a reduction in intensity as it is harder to vibrate fluid
How do we overcome this loss of intensity when waves are converted into fluids?
Impediance matching
This provides amplification