3. Hearing Flashcards
what is sound caused by?
changes in air pressure
how are these air pressure waves characterised?
These pressure waves are characterised by amplitude, frequency,
and phase.
what is amplitude?
loudness
Decibels: dB
what is frequency?
Pitch
Hertz; Hz
What is phase?
position within a cycle
what is a pure tone?
A sine wave, which is the simplest sound wave
what is the loudness of a space shuttle launce (from 45m)
180
What is the loudness of the Loudest Rock band?
160dB
What is the loudness pain threshold?
140 dB
What is the loudness of loud thunder?
120 dB
what is the loudness of the loudest record shout?
111 dB
What is the loudness of the heavy traffic noise?
100 dB
What is the loudnes of a vacuum cleaner?
80 dB
What is the loudness of a normal conversation?
60 dB
What is the loudness of a quiet office?
20 dB
What is the human hearing range?
20-20 000 Hz
What do most of our auditory experiences involve?
Most of our auditory experience involves only a small fraction of
this range
• e.g., typical vocal range: 80–1100 Hz
how are complex sounds built?
Complex sounds can be built up from series of sine waves of varying amplitude, frequency, and phase.
How can we decompose complex sounds?
We can decompose complex sounds into their sine wave components by a process called Fourier analysis.
What is the fundamental?
The lowest frequency component of a complex sound
What are many complex sounds made up of?
harmonics—integer
multiples of the fundamental
If the fundamental frequency is 440 Hz, then the 2nd harmonic will be
880 Hz, the 3rd harmonic will be 1320 Hz, and so on
What are the 4 main components of the ear?
Outer ear
Middle ear
Inner ear
Cochlear
What parts of the ear are in the outer ear?
Pinna, External auditory canal, eardrum
What does the Pinna do?
» increases the sound amplitude
» helps determine the direction from which a sound is coming
What does the external auditory canal do?
» provides protection
» increases the sound amplitude
What does the eardrum do and what is its scientific term?
(tympanic membrane)
» vibrates in response to sound waves
» moves bones in the middle ear
What is in the middle ear?
Ossicles
What are the types of Ossicles?
Malleus
Incus
Stapes
What are the smallest bones in the human body?
Ossicles
What do Ossicles do?
The ossicles transmit the vibration of the eardrum (with some
amplification) into the choclea through lever actions
They also provide protection against high amplitude sounds
Muscles attached to the ossicles restrict the bones’ movements
What does the inner ear consist of?
Semicircular canals and the cochlear
What do the cochlear contain?
sensory receptors and an oval window
What is the oval window?
- Membrane covering an opening in the cochlea
- The stapes is attached directly to the oval window (i.e., this is
where vibrations get into the cochlea) - The oval window is much smaller than the eardrum—this size
difference further helps amplify sound waves
What does the cochlear do?
The cochlea is filled with a watery liquid, which moves in response to the vibrations coming from the middle ear
What are the three canals in the cochlear?
» Vestibular canal
» Tympanic canal
» Cochlear duct
How are the three canals in the cochlear separated?
These canals are separated by:
• Reissner’s membrane
• Basilar membrane
Which vibrate in response to vibrations of the oval window
What is located o the Basilar membrane?
auditory receptor cells
hair cells) (in the cochlear duct
What happens when the basilar membrane vibrates?
When the basilar membrane vibrates, hair cells are also set in motion. This converts the vibrations into neural signals