2. Hearing

Question 1

Nature of sound:

sound caused by…

That are characterised by…

simplest sound wave is…

Answer 1

air pressure waves

amplitude (dB) - loudness
Frequency (Hz) - pitch
Phase - position within a cycle

a pure tone - sine wave

Question 2

Nature of sound:

sound caused by…

That are characterised by…

simplest sound wave is…

Answer 2

air pressure waves

amplitude (dB) - loudness
Frequency (Hz) - pitch
Phase - position within a cycle

a pure tone - sine wave

Question 3

human hearing range is …

Answer 3

20-20,000 Hx

Question 4

Typical vocal range…

Answer 4

80-1100Hx

Question 5

Nature of sound:

complec sounds can be built up from…

Answer 5

a series of sine waves with varying amplitudes, frequency and phase

can be decomposed into components by Fourier analysis

Question 6

Nature of sound:

what is the fundamental?
What are complex sounds made up of?

Answer 6

fundamental = lowest frequency component of a complex sound

many complex sounds are made up of harmonics, - integer multiples of the fundamental

Question 7

Basic physiology of the ear

components of the OUTER EAR

Answer 7

Pinna

• increases the sound amplitude
• Helps determine the direction from which a sound is coming form

External auditory canal

• provides protection
• increases the sound amplitude

Eardrum (tympanic membrane)
- vibrates in response to sound waves
Moves bones in the middle ear

Question 8

Basic physiology of the ear

Components of the MIDDLE EAR

Answer 8

ossicles

• Malleus
• Incus
• Stapes

smallest bones of human body

ossicles transmit the vibrations of the eardrum in to the cochlea through lever actions

They also provide protection against high amplitude sounds
- muscles attached to the ossicles restrict the bones’ movements

Question 9

Basic physiology of the ear

components of the INNER EAR

Answer 9

semicircular canals
- important for vestibular sense (sense of orientation)

Cochlea
- contains auditory sensory receptors

Question 10

Basic physiology of the ear

The cochlea

• oval window

Answer 10

The cochlear is filled with a watery liquid that moves in response to the vibrations coming from the middle ear

oval window

• membrane covering opening in the cochlea
• the stapes is attached directly to oval window (where the vibrations get into the cochlea
• much smaller than eardrum - size difference further helps amplify sounds waves

Question 11

Basic physiology of the ear

The cochlea canals

Answer 11

three canals of the cochlear

• vestibular canal
• tympanic canal
• cochlear duct

separated by

• Reissner’s membrane
• basilar membrane (on which hair/auditory receptor cells located in cochlear duct)

Question 12

Basic physiology of the ear

The cochlea canal and membrane orientation/order

Answer 12

vestibular canal
> Reissner's membrane 
>> cochlear duct 
>>> Basilar membrane
>>>>Tympanic membrane

Question 13

Basic physiology of the ear

vibrations to neural signals. HOW?

Answer 13

the three membranes vibrate in response to vibrations of the oval window

Wen the basilar membrane vibrates, hair cells are also set in motion

converts the vibrations in to neural signals

Question 14

the auditory cortex

What auditory tasks can be performed without the auditory cortex present?

Answer 14

• onset of sound
• changes in sound intensity
• Changes in sound frequency

Question 15

Typical vocal range…

Answer 15

80-1100Hx

Question 16

Nature of sound:

complec sounds can be built up from…

Answer 16

a series of sine waves with varying amplitudes, frequency and phase

can be decomposed into components by Fourier analysis

Question 17

Nature of sound:

what is the fundamental?
What are complex sounds made up of?

Answer 17

fundamental = lowest frequency component of a complex sound

many complex sounds are made up of harmonics, - integer multiples of the fundamental

Question 18

Basic physiology of the ear

components of the OUTER EAR

Answer 18

Pinna

• increases the sound amplitude
• Helps determine the direction from which a sound is coming form

External auditory canal

• provides protection
• increases the sound amplitude

Eardrum (tympanic membrane)
- vibrates in response to sound waves
Moves bones in the middle ear

Question 19

Basic physiology of the ear

Components of the MIDDLE EAR

Answer 19

ossicles

• Malleus
• Incus
• Stapes

smallest bones of human body

ossicles transmit the vibrations of the eardrum in to the cochlea through lever actions

They also provide protection against high amplitude sounds
- muscles attached to the ossicles restrict the bones’ movements

Question 20

Basic physiology of the ear

components of the INNER EAR

Answer 20

semicircular canals
- important for vestibular sense (sense of orientation)

Cochlea
- contains auditory sensory receptors

Question 21

Basic physiology of the ear

The cochlea

• oval window

Answer 21

The cochlear is filled with a watery liquid that moves in response to the vibrations coming from the middle ear

oval window

• membrane covering opening in the cochlea
• the stapes is attached directly to oval window (where the vibrations get into the cochlea
• much smaller than eardrum - size difference further helps amplify sounds waves

Question 22

Basic physiology of the ear

The cochlea canals

Answer 22

three canals of the cochlear

• vestibular canal
• tympanic canal
• cochlear duct

separated by

• Reissner’s membrane
• basilar membrane (on which hair/auditory receptor cells located in cochlear duct)

Question 23

Basic physiology of the ear

The cochlea canal and membrane orientation/order

Answer 23

vestibular canal
> Reissner's membrane 
>> cochlear duct 
>>> Basilar membrane
>>>>Tympanic membrane

Question 24

Basic physiology of the ear

vibrations to neural signals. HOW?

Answer 24

the three membranes vibrate in response to vibrations of the oval window

Wen the basilar membrane vibrates, hair cells are also set in motion

converts the vibrations in to neural signals

Question 25

Central auditory pathways nerve fibres from each cochlear synapse in a number of sites on the way to the primary cortex the pathway is...

Answer 25

``` The cochlear > The cochlear nucleus >> The superior olivary nucleus >>> The inferior colliculus >>>> The medial geniculate nucleus ``` NOTE: signal at cochlear nucleus splits and goes to each of the superior olivary nuclei > beyond this point, input from both ears is present in both hemispheres

Question 26

auditory space perception basilar membrane does not directly indicate sound locations so How is auditory space percived?

Answer 26

it is a biaural process - interaural time different >>onset difference >> phase difference - interaural intensity difference

Question 27

the auditory cortex comparing auditory jask abilities with and without the cortex, What can be concluded

Answer 27

the cortex deals with more complex auditory tasks while the lower structures deal with simple aspects of sound speech perception requires structures beyond the primary auditory cortex

Question 28

theories of encoding how do auditory system isolate and identify the frequencies of sounds. HOW?

Answer 28

basilar membrane is 30mm long with varying stiffness and widths along its length. Traveling waves move along the basilar membrane and peak at different points depending on the frequency of the sound Thus the location of the peak identifies the frequency of the sound stimulating auditory nerves at different cochlear locations leads to perception of sound in different pitch

Question 29

theories of encoding Who suffers from frequency specific hearing loss?

Answer 29

people who have damage to specific parts of the cochlea

Question 30

theories of encoding what are tonotopic maps?

Answer 30

maps present in the auditory system depict how auditory neurons are arranged in an orderly manner

Question 31

pitch perception monoaural encoding refers to...

Answer 31

how sound frequency is encoded in each ear i.e. cochlear nucleus pathway

Question 32

pitch perception biaural pitch encoding refers to...

Answer 32

how structures beyond the cochlear nucleus should be contributing to pitch perception missing fundamental can be perceived when harmonics are presented in one ear and can also be receive when presented in different jars

Question 33

Loudness perception what are the basic mechanisms of loudness perception

Answer 33

overall firing rate range of firing

Question 34

Loudness perception what factors affect loudness perception

Answer 34

sound duration - longer=louder frequency

Question 35

Loudness perception how does frequency effect loudness

Answer 35

generally higher frequencies are perceived to be louder as amplitude increases the effect of frequency becomes smaller

Question 36

auditory space perception in auditory space perception, you try to determine a sound's...

Answer 36

horizontal direction (azimuth) vertical direction distance

Question 37

auditory space perception describe interaural time diference

Answer 37

unless a sound is directly in front or behind, it reaches two ears at different times (onset difference) > detected by a simple "delay line" mechanisms in brain same sound will most likely be in two different phases when it reaches each ear (Phase difference) > but the phase difference is less useful for localising high-frequency sounds

Question 38

auditory space perception describe inter aural intensity diference

Answer 38

the same sound should be a bit more intense at the eat that is closer to the sound source > the energy of a sound decreases as it travels farther > the head works as a barrier that reduces the intensity of the sound (sound shadow) >> this effect is more pronounced for high frequency sounds

Question 39

auditory space perception How does frequency effect auditory space perception

Answer 39

interaural time difference (phase) is useful for localising low frequency sounds interaural intensity difference is useful for localising high frequency sounds

Question 40

auditory space perception How is head movement useful for auditory localisation

Answer 40

by changing the position of the ears you can experience changes in interaural time/intensity differences