Sensory Physiology

Question 1

Define amplitude.

Answer 1

Otherwise known as intensity. Measure as sound pressure in decibels (dB) - perceived as loudness.

Question 2

Define frequency.

Answer 2

Number of cycles per second of vibration, measured in hertz (Hz) and perceived as pitch.

Question 3

Define pinna.

Answer 3

The external part of the ear - a unique mammalian feature. Important for speech perception and sound localisation.

Question 4

Define ossicles.

Answer 4

Connect the tympanic membrane to the inner ear via the oval window.

Question 5

What do the tensor tympani and stapedius muscle do?

Answer 5

Act to improve perception and sound protection – both damaging sounds and those that are self-produced.

Question 6

Define cochlea.

Answer 6

A coil structure that consists of three parallel fluid-filled canals: vestibuli, media, tympani.

Question 7

What is the organ of Corti?

Answer 7

The structure responsible for converting the vibrations produced by the ossicles into neural activity.

Question 8

What are hair cells (sensory cells)?

Answer 8

• both inner and outer; are involved in transmitting the perturbations in the basilar membrane and transmit this information to the vestibulocochlear nerve.

Question 9

Name the three components of the organ of Corti.

Answer 9

• sensory cells (hair cells)
• auditory fibres that make up the vestibulocochlear nerve
• other supporting cells.

Question 10

What are the differences between inner and outer hair cells?

Answer 10

• Inner hair cells associated with many auditory cells nerves whereas outer hair cells only associate with a few.
• Inner hair cells are involved in sound perception however outer hair cells are not - they fine tune information by changing tension on the basilar membrane.

Question 11

What is used to inhibit the input from loud sounds?

Answer 11

Efferent projections from the brain.

Question 12

Define onset disparity.

Answer 12

The time difference it takes for sound to reach each ear. This results in an ongoing phase disparity.

Question 13

What are the common causes of conduction deafness?

Answer 13

External:
- Cerumen (excessive earwax)
- Otitis externa (ear infection)
Middle:
- Fluid accumulation in the eustachian tube.

Question 14

Define central deafness.

Answer 14

Hearing loss caused by brain lesions, with complex results e.g. word deafness, cortical deafness and amusia.

Question 15

What is conduction deafness?

Answer 15

Disorders of the outer or middle ear that prevent sounds being perceived.

Question 16

What is sensorineural deafness?

Answer 16

Originates from cochlear or auditory nerve lesions.

Question 17

What is word deafness?

Answer 17

Unable to recognize spoken words; speech production and simple sound discrimination are still functional.

Question 18

What is cortical deafness?

Answer 18

Difficulty in recognizing auditory stimuli; rare bilateral damage to the auditory cortex. Also stroke-induced damage to various nuclei in the auditory pathway.

Question 19

Define amusia.

Answer 19

An inability to discern music tunes; now beats. Localized to the right inferior frontal gyrus. It is associated with greater cortical grey matter, the increased cortical thickness is proposed to inhibit cortical functioning.

Question 20

Describe the organisation of the basilar membrane.

Answer 20

Topographical organisation - different regions respond to different frequencies.

Question 21

What is the superior olivary nucleus?

Answer 21

The main localisation nucleus for sound with two divisions: lateral superior olive and medial superior olive.

Question 22

What is the lateral superior olive?

Answer 22

Part of superior olivary nucleus - processes intensity difference.

Question 23

What is the medial superior olive?

Answer 23

Part of superior olivary nucleus - processes latency differences, but encodes sound by relative activity of the left and right sides.