👂🏻 Hearing

What are the two key dimensions of sound?

Intensity and frequency

What is intensity?

The amplitude of the sound wave, corresponding with the loudness of a sound

What is intensity measured by?

Decibles (dB)

What is frequency?

The wavelength of the sound wave, determining the pitch we perceive

What is frequency measured in?

Hertz (Hz)

What is timbre?

The quality that allows us to distinguish between different voices or instruments

What are the two main structures making up the outer ear?

The pinna and the auditory canal

What is the pinna?

Collects sound waves from the environment and funnels them inward

What is the purpose of the auditory canal?

Helps to amplify certain frequencies

What is the purpose of the middle ear?

When they convert from air-borne vibrations into mechanical movement

What is another name for the eardrum?

Tympanic membrane

What is the the first structure of the middle ear?

The eardrum

What are the ossicles?

A chain of three tiny bones (the smallest bones in the body)

What are the names of the three ossicles?

Malleus, incus/anvil and stapes

What is the malleus attached to?

Tympanic membrane

What is the most important structure in the inner ear?

Cochlea

What is in the cochlea?

Contains the specialised sensory cells responsible for transducing sound

What is the role of semicircular canals?

Detecting rotational movement and helping to maintain balance and spatial orientation

What are the spiral ganglia neurons?

Communicate directly with the cochlear hair cells

What does MGN stand for?

Medial geniculate nucleus

What are the two sets of fluid-filled cavities embedded in the temporal bone of the skull?

Semicircular canals and the cochlea

How many chambers are in the cochlea?

3

What are the three chambers in the cochlea?

Vestibular canal

Tympanic canal

Cochlear duct

Which duct contains the fluid endolymph?

The cochlear duct

The endolymph is rich in _______ and low in _______

Potassium and sodium

What separates the vestibular canal and cochlear duct?

Reissner’s membrane

What separates the tympanic canal and cochlear duct?

Basilar membrane

The _________ window covers the tympanic canal

Oval

What is found within the cochlear duct?

The organ of Corti

How many rows of hair cells are in the organ of Corti?

2 rows

Where are the inner hair cells located?

Near the conenction between the tectorial membrane and the cochlear duct

Are spiral ganglion neurons bipolar or unipolar?

Bipolar

What do the spiral ganglion neurons connect?

Connects the hair cells of the cochlea with the brain

Where is the primary auditory cortex located?

The temporal lobe, just below the lateral sulcus

How is the primary auditory cortex organised?

Organised in columns

How can pitch vary?

Frequency, the intensity or context of a stimulus

What is tonotopic organisation?

Describes the fact that neurons responding to one frequency are located next to neurons responding to similar frequencies

What do decibles describe?

The physical qualities of the sound stimulus

What are auditory neurons?

Can respond to higher sound amplitudes by increasing their rate of response

What is the purpose of the superior olive?

Distinctions between the arrival times of sound at each ear

What is conduction loss?

Results from a buildup of wax in the ear canal, infections of the middle ear and otosclerosis

Can a hearing aid help with conduction loss?

Yes

What is the purpose of the vestibular system?

Provides information about the position and movements of our head, contributing to balance