Audiogram and Sound Intensity Practical No. 2

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Questions and Answers

Sound amplification in the outer ear (auditory canal) is affected by:

  • Sound pressure (correct)
  • Sound speed
  • Sound amplitude

Prolonged exposure to loud noise can cause permanent damage to:

  • The air conductivity (of the ear)
  • The structure of the eardrum (tympanic membrane)
  • Inner ear (correct)

The loss of elasticity (stiffening) of the tympanic membrane will result in:

  • Decrease in the binaural effect
  • Increase of air conductivity
  • Decrease of hearing threshold (correct)

Sound intensity level (dB) and Loudness (phones) will have the same magnitude at the following frequency: (ref. the equal-loudness graph, Fig.1)

<p>1000 Hz (C)</p> Signup and view all the answers

Refer to the equal-loudness curve above. At frequency of 4000 Hz the perceived sound is:

<p>Louder than at 1000 Hz (B)</p> Signup and view all the answers

Sound Intensity Level is proportional to the logarithm of the ratio of incoming to threshold intensity SIL = 10·Log (I/I‰). If intensity is increased by a factor of 100, what is change in SIL?

<p>Increase with 20 dB (plus 20dB) (C)</p> Signup and view all the answers

The sound intensity level in a room is 20 dB. A TV produces additional intensity level of 60 dB. What is the sound intensity in the room now?

<p>80 dB</p> Signup and view all the answers

Match the physical (objective) with the corresponding psychophysical (subjective) properties of the sound: (hint: multiple connections are possible)

<p>Frequency = Timbre Intensity = Pitch Acoustic spectrum = Loudness</p> Signup and view all the answers

Sound frequency is:

<p>Physical property (objective) (B)</p> Signup and view all the answers

The fundamental harmonic (frequency fo) in a complex sound is characterized by:

<p>The lowest frequency and highest amplitude (C)</p> Signup and view all the answers

The speed of sound is calculated by the Newton-Laplace formula c = $\sqrt{\frac{K}{\rho}}$ where K is the stiffness coefficient, and p is the density of the material. If the density of the substance doubles, the speed of propagating sound wave will:

<p>Decrease (C)</p> Signup and view all the answers

What is the speed of sound in air?

<p>330 m/s</p> Signup and view all the answers

Does absorption of sound and the corresponding penetration depth depend on the wavelength?

<p>True (A)</p> Signup and view all the answers

Is it possible for internal organs to generate sounds that propagate to the skin, and are audible?

<p>True (A)</p> Signup and view all the answers

Noise can be defined as:

<p>Superposition of random sound vibrations, with frequency and amplitude constantly changing in time. (B)</p> Signup and view all the answers

Damping oscillations are:

<p>Oscillations with decreasing amplitude (B)</p> Signup and view all the answers

If the amplitude of a wave doubles (x2), what would happen to the period?

<p>There will be no change (A)</p> Signup and view all the answers

In which of the following mediums, sound waves cannot propagate?

<p>Vacuum (B)</p> Signup and view all the answers

Which of the following waves are NOT mechanical?

<p>Light (A)</p> Signup and view all the answers

A propagating sound wave transfers:

<p>Energy (A)</p> Signup and view all the answers

Which of the following factors has the most significant effect on the speed of propagation of sound waves?

<p>Elastic properties of the medium (B)</p> Signup and view all the answers

Sound waves are:

<p>Mechanical waves (C)</p> Signup and view all the answers

The speed of sound (in non-dispersive medium):

<p>Depends on the properties of the propagating medium (B)</p> Signup and view all the answers

Human ear is most sensitive to frequencies (refer to equal-loudness curve):

<p>From 2000 Hz to 5000 Hz (A)</p> Signup and view all the answers

What is the meaning of 0 dB?

<p>The sound is at threshold reference level (B)</p> Signup and view all the answers

Timbre is:

<p>Psychophysical (subjective) sound property (A)</p> Signup and view all the answers

The pitch of sound depends mostly on:

<p>Sound frequency (C)</p> Signup and view all the answers

Which of the following does NOT have relevance to the reflection/transmission of sound waves?

<p>The colors of substances near the boundary area (A)</p> Signup and view all the answers

Timbre is related to:

<p>Harmonic overtones (B)</p> Signup and view all the answers

Weber-Fechner law (in psychophysics) describes a logarithmic relationship between the intensity of a sound wave and....:

<p>The perception of loudness (C)</p> Signup and view all the answers

Intensity is defined as:

<p>Power per area (C)</p> Signup and view all the answers

When sound wave travels across two materials with similar acoustic impedance, at the boundary surface there will be:

<p>more transmission and less reflection (B)</p> Signup and view all the answers

The acoustic impedance Z of a substance is defined as the product of:

<p>The density and the speed of sound: pv (A)</p> Signup and view all the answers

Why can't we hear voices (speech) when submerged under water?

<p>Most of the sound is reflected at the air/water boundary (C)</p> Signup and view all the answers

What property of sound is measured in decibels (dB)?

<p>Intensity level (A)</p> Signup and view all the answers

If the period of a wave is 0.02 s, what is its frequency? (Hint: how often does it vibrate in one second?)

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Flashcards

What is an audiogram?

The measurement of sound intensity at different frequencies to evaluate hearing loss.

What affects sound amplification in the outer ear?

Sound amplification in the auditory canal increases with the sound pressure.

What part of the ear is most vulnerable to noise damage?

Prolonged exposure to loud noise can damage the delicate structures of the inner ear, leading to permanent hearing loss.

What happens to hearing threshold when the tympanic membrane stiffens?

A decrease in the hearing threshold occurs when the tympanic membrane loses its elasticity, making it harder to vibrate and transmit sound.

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At what frequency do dB and phones have the same value?

1000 Hz is the frequency where sound intensity level (dB) and loudness (phones) are equal on the equal-loudness graph.

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How does perceived loudness change from 1000 Hz to 4000 Hz?

At 4000 Hz, the perceived sound is louder than at 1000 Hz on the equal-loudness curve.

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How does SIL change if intensity increases by 100 times?

If intensity increases by a factor of 100, SIL increases by 20 dB. This is because SIL is proportional to the logarithm of the intensity ratio.

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What is the total sound intensity level in a room with 20 dB and a TV at 60 dB?

The total sound intensity level in the room will be approximately 60 dB. Sound intensity levels add in a logarithmic manner.

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What is the difference between sound frequency and timbre?

Frequency is the objective physical property of sound. It is the rate at which sound waves vibrate, whereas timbre refers to the subjective quality of a sound.

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What characterizes the fundamental harmonic in a complex sound?

The lowest frequency in a complex sound with the highest amplitude is called the fundamental harmonic.

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How does the speed of sound change if density doubles?

If the density of a substance doubles, the speed of sound will decrease because it is inversely proportional to the square root of density.

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What is the approximate speed of sound in air?

The speed of sound in air is approximately 330 m/s.

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How does sound absorption relate to wavelength?

Absorption of sound depends on the wavelength. Longer wavelengths are less absorbed and penetrate deeper.

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Can internal organs produce audible sounds?

Internal organs can generate sounds that propagate through tissues and can be audible at the skin surface.

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How is noise defined in terms of sound waves?

Noise is characterized by random sound vibrations with constantly changing frequency and amplitude.

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What does damping mean in terms of oscillations?

Damping oscillations have decreasing amplitude over time.

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How does the wave period change when the amplitude doubles?

The period of a wave remains unchanged when the amplitude doubles. Period is determined by the frequency, not the amplitude.

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In what medium can sound waves NOT propagate?

Sound waves cannot propagate through vacuum because they need a medium to travel.

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Which of the following are NOT mechanical waves?

Light waves are not mechanical waves, unlike water waves and sound waves.

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What does a propagating sound wave transfer?

A propagating sound wave transfers energy through a medium but doesn't transfer matter itself.

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What factor influences the speed of sound waves most significantly?

The elastic properties of the medium have the greatest influence on the speed of sound wave propagation.

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What type of waves are sound waves?

Sound waves are mechanical waves that require a medium to travel.

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How does the speed of sound change in different mediums?”,

The speed of sound is dependent on the properties of the medium it travels through. It is not constant and does not decrease as sound moves away from the source.

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Study Notes

Practical No. 2 - Audiogram

  • Audiogram: a diagnostic method for the hearing apparatus
  • Sound amplification in the outer ear is affected by sound speed, sound pressure, and sound amplitude.
  • Prolonged exposure to loud noise can damage the air conductivity, eardrum (tympanic membrane), and inner ear.
  • Loss of elasticity in the tympanic membrane leads to decreased hearing threshold and reduced binaural effect.
  • Sound intensity level (dB) and loudness (phones) have the same magnitude at 1000 Hz (according to the equal-loudness graph).

Practical No. 2 - Sound Intensity

  • Sound intensity level (dB) and loudness (phones) have the same magnitude at 1000 Hz.
  • Sound intensity level is proportional to the logarithm of the ratio of incoming intensity to threshold intensity (SIL = 10·Log (I/I‰)).
  • Increasing intensity by a factor of 100 increases SIL by 20 dB.

Practical No. 2 - General

  • The equal-loudness curve shows the relationship between perceived sound loudness and frequency.
  • At 4000 Hz, the perceived sound is softer than at 1000 Hz (according to the equal-loudness curve).

Practical No. 3 - General

  • Sound waves cannot propagate in a vacuum.
  • Sound waves are mechanical waves.
  • Sound waves transfer energy, not matter.
  • The speed of sound is most affected by the elastic properties of the medium.
  • Human ears are most sensitive to frequencies between 2000 Hz and 5000 Hz.
  • 0 dB corresponds to the lowest detectable sound level.
  • Timbre is the subjective quality of a sound.
  • Pitch is largely determined by frequency.
  • Sound intensity level is measured in decibels (dB).

Practical No. 7 - Alternating Current

  • Alternating current (AC) changes direction.
  • An oscilloscope measures the relationship between two variables, such as time and voltage.
  • Electric current is measured in amps (A).
  • Electric current represents the rate of charge per unit time (Q/t).
  • Electric current relates to the rate of charge flow, whether in a circuit or in a vacuum tube (where electric current is measured in terms of electrons per unit time).

Practical No. 7 - General

  • In metallic conductors, current doubles with the doubling of voltage (if resistance remains constant).
  • Resistors have a direct relationship between voltage (V) and current (I).
  • Ohm's Law defines the relationship as I = V/R (where R is resistance).

Practical No. 8 - Electromagnetic Waves

  • High frequency currents are more dangerous to humans than Low frequency currents.
  • High frequency currents often cause deeper tissue heating effects compared to lower frequency currents.
  • Pulsed current often has less potential for differential tissue heating when used to effect stimulation than other current types.

Practical No. 8 - General

  • Skin and fat tissue have the lowest thermal conductivity among the listed organs and tissues.
  • High-frequency electric current therapy can result in deep tissue heating.

Practical No. 9 - Optical Microscope

  • To obtain a good quality image with an optical microscope, the object must be placed at a distance greater than the focal length of the objective, but less than twice its focal length or at the focal point.
  • The image formed by the eyepiece is a virtual image.
  • Magnification involves linear and angular aspects (and is related to the optical power of the objective and ocular).
  • The highest resolution of standard optical microscopes is 0.2 μm.

Practical No. 10 - Eye Refraction

  • Near-sightedness (myopia) is corrected with concave lenses.
  • Far-sightedness (hyperopia) is corrected with convex lenses.
  • Astigmatism is corrected with cylindrical lenses.
  • The human eye is most sensitive to green light.

Practical No. 11 - Laser

  • Lasers operate by stimulated emission.
  • A population inversion is a state in which more electrons are in higher energy states than lower.
  • Lasers use optical resonators.

Practical No. 12 - Radiopharmaceuticals and Nuclear Medicine

  • Specific types of nuclear decay, such as beta minus or gamma decay, are suitable for in vivo diagnostics.

Practical No. 13 - Radioactivity, Gamma-Rays

  • In general, gamma radiation has more penetration depth in tissue than alpha or beta radiation
  • The activity of a radionuclide is the rate of decay measured in Becquerels (Bq).
  • Radiopharmaceuticals are drugs containing radioactive elements, often used for diagnostic purposes. This can include measuring the rate of decay in tissues or organs using imaging techniques (that measure the emissions).

Practical No. 14 - Gamma Radiation, Photon Energy, and Radiotherapy

  • The predominant form of interaction in radiotherapy with high energy radiation sources (such as gamma rays) is often the compton effect (scattering).
  • Gamma rays have a higher penetration depth.

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