The pinna (ear flap) reflects sound waves into the auditory canal, concentrating energy onto a smaller area and increasing intensity. This allows very quiet sounds to be detected.

What are the three main regions of the human ear?

The outer ear , middle ear and inner ear .

What is the function of the Eustachian tube ?

It equalises pressure differences between the air in the middle ear and the air outside the ear. It connects the middle ear cavity to the nasopharynx (throat).

Name the three ossicles of the middle ear, in order from the ear drum to the oval window.

The malleus (hammer), incus (anvil) and stapes (stirrup).

The ossicles act as a system of levers, amplifying vibrations of the tympanic membrane by about .......... , or 50%.

The ossicles act as a system of levers, amplifying vibrations of the tympanic membrane by about 1.5 times , or 50%.

What is the function of the round window ?

It allows movement of fluid in the cochlea by relieving pressure. As the stapes pushes the oval window inwards, the round window bulges outwards to compensate.

Why are high-frequency sounds detected at the base of the cochlea, while low-frequency sounds are detected at the apex?

Different regions of the basilar membrane have different natural frequencies , so different frequencies of sound resonate at different points along the cochlea.

True or False? The oval window has a smaller area than the ear drum, which decreases the pressure of the vibrations reaching the cochlea.

False. Since pressure = force / area , a smaller area at the oval window (about 1/15 of the ear drum) combined with the force amplification from the ossicles (about 1.5 times) causes the pressure on the oval window to be over 20 times greater than on the ear drum.

Define the intensity of a sound wave.

The amount of sound energy that passes a point per second per unit area .

Define the threshold of hearing , I 0 .

The lowest intensity that a normal human ear can detect, at a frequency of 1 kHz. This is equal to about 1 × 10 -12 W m -2 .

The auditory canal acts as a closed tube resonator, with an antinode forming at the .......... end and a node forming at the closed end.

The auditory canal acts as a closed tube resonator, with an antinode forming at the open end and a node forming at the closed end.

To which frequency range is the human ear most sensitive, and why is this useful?

About 2 to 5 kHz (around 3000 Hz), which corresponds to the frequencies of human speech .

True or False? The combined intensity level of two equally loud sounds can be found by simply adding their individual decibel values together.

False. The decibel scale is logarithmic , so intensity levels cannot be added directly. Each value must first be converted into an intensity (W m -2 ), the intensities added, and the total converted back into decibels.

Define an equal loudness curve .

A plot of intensity level (in dB) against frequency (in Hz), where all sounds on the curve are perceived as equally loud .

What reference frequency is used to generate an equal loudness curve?

1 kHz . A reference sound at this frequency and a fixed intensity level is compared against sounds of other frequencies, whose intensity level is adjusted until they are perceived as equally loud.

Why do both axes of an equal loudness curve use a logarithmic scale?

To match the very large range of intensities and frequencies that the human ear can detect.

The equal loudness curve for a normal ear has a .......... shape, with the lowest point (greatest sensitivity) at about 3000 Hz.

The equal loudness curve for a normal ear has a U-shape , with the lowest point (greatest sensitivity) at about 3000 Hz.

Define the dBA scale .

An adjusted decibel scale used to calibrate sound-level meters, giving relative measurements that take into account the ear's response to different frequencies.

At what frequency do the dB and dBA scales always give the same reading?

1 kHz , the reference frequency, where both scales are set to be identical.

True or False? The dBA scale gives a flat response across all frequencies, just like the dB scale.

False. The dB scale is flat because it is not frequency dependent. The dBA curve peaks at around 3 kHz to simulate the ear's peak sensitivity, then decreases at frequencies above and below this.

How does the shape of the dBA curve compare with the shape of the equal loudness curve?

The dBA curve has the inverse shape to the equal loudness curve.

What are three causes of hearing deterioration?

Age , exposure to excessive and prolonged noise , and genetic factors and disease .

Describe the pattern of hearing loss caused by ageing .

Occurs at all frequencies , with the greatest losses at higher frequencies .

Describe the pattern of hearing loss caused by exposure to excessive noise .

Occurs in the frequency range the person was exposed to, with the greatest loss at 4 kHz .

Hearing loss due to excessive noise causes the greatest loss at a frequency of about .......... .

Hearing loss due to excessive noise causes the greatest loss at a frequency of about 4 kHz .

How can the degree of a person's hearing loss be tested?

By obtaining their equal loudness curve and comparing it with the curve for normal hearing .

True or False? Age-related hearing loss only affects high frequencies, while noise-induced hearing loss affects all frequencies equally.

False. It is the opposite pattern: hearing loss due to ageing occurs at all frequencies (worst at high frequencies), while hearing loss due to excessive noise is localised to the frequency range of exposure, peaking at 4 kHz.

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Physics of the Ear (AQA A Level Physics): Flashcards

Exam code: 7408

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FrontStructure of the Ear
Define pinna.

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Cards in this collection (29)

Define pinna.
The pinna (ear flap) reflects sound waves into the auditory canal, concentrating energy onto a smaller area and increasing intensity. This allows very quiet sounds to be detected.
What are the three main regions of the human ear?
The outer ear, middle ear and inner ear.
What is the function of the Eustachian tube?
It equalises pressure differences between the air in the middle ear and the air outside the ear. It connects the middle ear cavity to the nasopharynx (throat).
Name the three ossicles of the middle ear, in order from the ear drum to the oval window.
The malleus (hammer), incus (anvil) and stapes (stirrup).
The ossicles act as a system of levers, amplifying vibrations of the tympanic membrane by about .........., or 50%.
The ossicles act as a system of levers, amplifying vibrations of the tympanic membrane by about 1.5 times, or 50%.
What is the function of the round window?
It allows movement of fluid in the cochlea by relieving pressure. As the stapes pushes the oval window inwards, the round window bulges outwards to compensate.
Why are high-frequency sounds detected at the base of the cochlea, while low-frequency sounds are detected at the apex?
Different regions of the basilar membrane have different natural frequencies, so different frequencies of sound resonate at different points along the cochlea.
True or False?
The oval window has a smaller area than the ear drum, which decreases the pressure of the vibrations reaching the cochlea.
False.
Since pressure = force / area, a smaller area at the oval window (about 1/15 of the ear drum) combined with the force amplification from the ossicles (about 1.5 times) causes the pressure on the oval window to be over 20 times greater than on the ear drum.
Define the intensity of a sound wave.
The amount of sound energy that passes a point per second per unit area.
State the equation for the intensity of a sound wave that spreads out uniformly as a spherical shell, in terms of power P and distance r from the source.
$I = \frac{P}{4 π r^{2}}$
Define the threshold of hearing, I₀.
The lowest intensity that a normal human ear can detect, at a frequency of 1 kHz. This is equal to about 1 × 10^-12 W m^-2.
State the equation for the intensity level (in decibels) of a sound of intensity I.
$intensity level = 10 \log (\frac{I}{I_{0}})$
where I₀ is the threshold of hearing.
The auditory canal acts as a closed tube resonator, with an antinode forming at the .......... end and a node forming at the closed end.
The auditory canal acts as a closed tube resonator, with an antinode forming at the open end and a node forming at the closed end.
To which frequency range is the human ear most sensitive, and why is this useful?
About 2 to 5 kHz (around 3000 Hz), which corresponds to the frequencies of human speech.
True or False?
The combined intensity level of two equally loud sounds can be found by simply adding their individual decibel values together.
False.
The decibel scale is logarithmic, so intensity levels cannot be added directly. Each value must first be converted into an intensity (W m^-2), the intensities added, and the total converted back into decibels.
Define an equal loudness curve.
A plot of intensity level (in dB) against frequency (in Hz), where all sounds on the curve are perceived as equally loud.
What reference frequency is used to generate an equal loudness curve?
1 kHz. A reference sound at this frequency and a fixed intensity level is compared against sounds of other frequencies, whose intensity level is adjusted until they are perceived as equally loud.
Why do both axes of an equal loudness curve use a logarithmic scale?
To match the very large range of intensities and frequencies that the human ear can detect.
The equal loudness curve for a normal ear has a .......... shape, with the lowest point (greatest sensitivity) at about 3000 Hz.
The equal loudness curve for a normal ear has a U-shape, with the lowest point (greatest sensitivity) at about 3000 Hz.
Define the dBA scale.
An adjusted decibel scale used to calibrate sound-level meters, giving relative measurements that take into account the ear's response to different frequencies.
At what frequency do the dB and dBA scales always give the same reading?
1 kHz, the reference frequency, where both scales are set to be identical.
True or False?
The dBA scale gives a flat response across all frequencies, just like the dB scale.
False.
The dB scale is flat because it is not frequency dependent. The dBA curve peaks at around 3 kHz to simulate the ear's peak sensitivity, then decreases at frequencies above and below this.
How does the shape of the dBA curve compare with the shape of the equal loudness curve?
The dBA curve has the inverse shape to the equal loudness curve.
What are three causes of hearing deterioration?
Age, exposure to excessive and prolonged noise, and genetic factors and disease.
Describe the pattern of hearing loss caused by ageing.
Occurs at all frequencies, with the greatest losses at higher frequencies.
Describe the pattern of hearing loss caused by exposure to excessive noise.
Occurs in the frequency range the person was exposed to, with the greatest loss at 4 kHz.
Hearing loss due to excessive noise causes the greatest loss at a frequency of about ...........
Hearing loss due to excessive noise causes the greatest loss at a frequency of about 4 kHz.
How can the degree of a person's hearing loss be tested?
By obtaining their equal loudness curve and comparing it with the curve for normal hearing.
True or False?
Age-related hearing loss only affects high frequencies, while noise-induced hearing loss affects all frequencies equally.
False.
It is the opposite pattern: hearing loss due to ageing occurs at all frequencies (worst at high frequencies), while hearing loss due to excessive noise is localised to the frequency range of exposure, peaking at 4 kHz.

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