C: The bell matches the impedance of the air and the skin by resonating with the sounds coming from the body.

A: This sound pressure level (or perhaps even 85 dB) will produce hearing damage with long-term exposure. The decibel is not a statement about frequency. 0 dB is the threshold of human hearing. Different frequencies if all played at 90 dB would be perceived as different in loudness.

C: Atmospheric air pressure decreases as altitude increases. The air trapped in the middle ear remains at atmospheric pressure if we rapidly gain altitude, so this trapped air volume in the middle ear expands (Boyle’s law). This causes the ear drum to be uncomfortably deformed outwards. When the Eustachian tube (which is normally squashed flat) opens to allow some air to escape from the middle ear compartment, comfort is restored. This is sometimes experienced in a flight when the plane takes off from the ground and rises into the air.

A: The cochlea contains the organ of Corti (the spiral organ) and its basilar membrane.

B: When the cochlear fluid moves, it displaces the basilar membrane which pushes the hair cells within the organ of Corti against the tectorial membrane.

D: Malleus, stapes and incus (aka hammer, stirrup, anvil) are in the middle ear. The stapedius is a muscle, while the cochlea is the inner ear.

C: The tensor tympani pulls the malleus and stiffens the ear drum, while the stapedius pulls the stapes to reduce its movement against the oval window. In this way, the damage that loud sounds may do to the hearing mechanism is reduced.

A: The cochlea contains liquids known as perilymph and endolymph. The Eustachian tube is usually squashed flat, but when it is opened, it contains air that is entering or leaving the middle ear.

A: The ear as a hearing mechanism is able to better able to respond (detect) frequencies near 3000 Hz, whereas frequencies near 50 Hz are almost inaudible.

A: Meatus is a canal like tube, for example, the external acoustic meatus (of the temporal bone), urethral meatus (of the penis) and nasal meatus.

B: The cochlea contains the scala vestibuli and the scala tympani, both of which are filled with perilymph. It also contains the cochlear duct filled with endolymph.

C: The air in the external ear canal resonates (at about 3000 Hz), the ossicles are a lever system that amplifies the movement of the tympanic membrane; the oval window, being about one twentieth the size of the tympanic membrane, also amplifies the pressure applied to the cochlear fluid compared to that applied to the tympanic membrane.

A: The basilar membrane is located in the inner ear and separates the scala tympani from the scala vestibuli. The tectorial membrane arches over the organ of Corti, while the tympanic membrane is the ear drum.

D: Both perilymph and endolymph are contained in the scalae of the cochlea and the semi-circular canals of the labyrinth. The middle ear contains air.

B: The tectorial membrane lies over the hair cells of the organ of Corti (which sits on the basilar membrane).

C: The hairs (stereocilia) of the hair cells are stimulated when our head tilts. Hair cells are embedded within the supporting cells. Otoliths are not cells.

B: The middle (not outer) ear is filled with air and is vented to the mouth via the Eustachian tube

C: The tympanic membrane (ear drum) is the first structure. The ossicles pass on the vibrations to the oval (not round) window of the cochlea.

D: The ossicles are mechanical lever systems that are attached to the tympanic membrane at one end and to the oval window at the other. They transmit the movements in the tympanic membrane across the middle ear and to the perilymph behind the oval “window”.

C: The inferior colliculi receive auditory stimuli via the medulla oblongata. The superior colliculi receive visual sensation. The arbor vitae (Latin for “tree of life”) brings sensory and motor information to and from the cerebellum.

B: Sound impinges on the tympanic membrane first. The Eustachian tube and the auditory tube are the same thing and do not conduct sound – they connect the middle ear to the mouth.

A: A special sense is one that is localised into a specific organ such as the ear. Sight is also a special sense being localised in the eye. The sense of touch is not localised as the entire skin is sensitive to touch.

A: The tensor tympani limits the amount of movement in the tympanic membrane. The stapedius reduces the movement of the stapes against the oval window.

A: Sound travels from the air in the outer ear to the middle ear by vibrating the tympanic membrane (the ear drum). Sound enters the cochlea (inner ear) via the oval window. The tectorial membrane (TM) is one of two acellular membranes in the cochlea of the inner ear, the other being the basilar membrane (BM). “Tectorial” in anatomy means forming a cover.

A: The cochlea and the three semi-circular canals of the inner ear are filled with fluid.

B: Intensity and amplitude are related. Our ear perceives some frequencies to be louder than others.

B: 60 dB is approximately the sound level of normal conversation, while the human ear is very sensitive to a frequency of 1000 Hz. 20 Hz is below our hearing range, while 21,000 Hz is beyond our range. 10 dB is very quiet compared to 60 dB.

A: Conductive loss is used to describe the situation where sound is not conducted well to the inner ear, which is otherwise healthy. The other three choices are different names for the same thing which is damage to the cochlea or auditory nerve.

B: The organ of Corti in the inner ear generates auditory nerve impulses when the hair cells are stimulated. If some of the hair cells are damaged, they cannot produce impulses in the auditory nerve

B: The stapes presses onto the oval window to transmit the vibration of the tympanic membrane to the cochlear fluid.