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Questions and Answers
What describes the resonant frequencies of a tube open at both ends?
What describes the resonant frequencies of a tube open at both ends?
Which frequency range defines normal human hearing?
Which frequency range defines normal human hearing?
What is the threshold intensity level that defines the lowest audible intensity?
What is the threshold intensity level that defines the lowest audible intensity?
What determines the perception of pitch in sound?
What determines the perception of pitch in sound?
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How are the fundamental frequency and overtones calculated for a tube open at both ends compared to one closed at one end?
How are the fundamental frequency and overtones calculated for a tube open at both ends compared to one closed at one end?
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What is the maximum sensitivity frequency range for the human ear?
What is the maximum sensitivity frequency range for the human ear?
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What distinguishes a phon from a decibel?
What distinguishes a phon from a decibel?
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What phenomenon is described as the perception of sound intensity?
What phenomenon is described as the perception of sound intensity?
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What happens to sounds below 20 Hz?
What happens to sounds below 20 Hz?
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What type of hearing loss can be partially overcome by sending sound vibrations through the skull?
What type of hearing loss can be partially overcome by sending sound vibrations through the skull?
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Which statement is true regarding cochlear implants?
Which statement is true regarding cochlear implants?
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Which of the following correctly describes the structure of a closed organ pipe supporting its first overtone?
Which of the following correctly describes the structure of a closed organ pipe supporting its first overtone?
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How many electrodes are typically found in a cochlear implant's array?
How many electrodes are typically found in a cochlear implant's array?
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What acoustic property does the external microphone of a cochlear implant primarily handle?
What acoustic property does the external microphone of a cochlear implant primarily handle?
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Which component of a cochlear implant is responsible for selecting certain frequencies?
Which component of a cochlear implant is responsible for selecting certain frequencies?
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What is a limitation of auditory amplification for hearing loss due to cochlear nerve damage?
What is a limitation of auditory amplification for hearing loss due to cochlear nerve damage?
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What occurs at the closed end of a tube that affects the formation of standing waves?
What occurs at the closed end of a tube that affects the formation of standing waves?
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What is the relationship between harmonics and the fundamental frequency in a tube closed at one end?
What is the relationship between harmonics and the fundamental frequency in a tube closed at one end?
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Given the formula for the fundamental frequency, $f_n = \frac{nv}{4L}$, what does 'n' represent?
Given the formula for the fundamental frequency, $f_n = \frac{nv}{4L}$, what does 'n' represent?
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If the length of a tube closed at one end is equal to one-fourth of the wavelength, how is the wavelength related to the length of the tube?
If the length of a tube closed at one end is equal to one-fourth of the wavelength, how is the wavelength related to the length of the tube?
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How many nodes and antinodes does the second overtone of a closed pipe consist of?
How many nodes and antinodes does the second overtone of a closed pipe consist of?
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What distinguishes a tube open at both ends from a tube closed at one end in terms of resonant behavior?
What distinguishes a tube open at both ends from a tube closed at one end in terms of resonant behavior?
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What formula represents the frequency of the fourth overtone in a tube closed at one end?
What formula represents the frequency of the fourth overtone in a tube closed at one end?
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At what point in a tube closed at one end is maximum air displacement found?
At what point in a tube closed at one end is maximum air displacement found?
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What factors primarily determine the speed of sound in a medium?
What factors primarily determine the speed of sound in a medium?
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How does temperature affect the speed of sound in air?
How does temperature affect the speed of sound in air?
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What is the relationship between frequency and wavelength for sound waves?
What is the relationship between frequency and wavelength for sound waves?
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What is the frequency of sound with a 0.10-m wavelength in air if the speed of sound is 340 m/s?
What is the frequency of sound with a 0.10-m wavelength in air if the speed of sound is 340 m/s?
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How is sound intensity related to its pressure amplitude?
How is sound intensity related to its pressure amplitude?
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What is the formula used to calculate the average speed of particles in a gas related to temperature?
What is the formula used to calculate the average speed of particles in a gas related to temperature?
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Why do sound waves travel faster in liquids and solids compared to gases?
Why do sound waves travel faster in liquids and solids compared to gases?
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What is the speed of sound when a frequency of 1500 Hz is associated with a wavelength of 0.221 m?
What is the speed of sound when a frequency of 1500 Hz is associated with a wavelength of 0.221 m?
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In what range does the speed of sound remain nearly independent of frequency in open air?
In what range does the speed of sound remain nearly independent of frequency in open air?
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What is the sound intensity level in decibels for a sound with an intensity of $4.00 \times 10^{-2}$ W/m2?
What is the sound intensity level in decibels for a sound with an intensity of $4.00 \times 10^{-2}$ W/m2?
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At what decibel level is the threshold of hearing defined?
At what decibel level is the threshold of hearing defined?
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What is a characteristic effect of low-frequency sounds compared to high-frequency sounds?
What is a characteristic effect of low-frequency sounds compared to high-frequency sounds?
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Which physical property of sound waves is primarily illustrated by the relationship $v_w = f\lambda$?
Which physical property of sound waves is primarily illustrated by the relationship $v_w = f\lambda$?
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What is the intensity of a sound wave traveling in 20°C air with a pressure amplitude of 0.5 Pa?
What is the intensity of a sound wave traveling in 20°C air with a pressure amplitude of 0.5 Pa?
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What power per unit area defines sound intensity?
What power per unit area defines sound intensity?
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What effect does the Doppler effect have on the perceived pitch of a sound as the source approaches and then moves away?
What effect does the Doppler effect have on the perceived pitch of a sound as the source approaches and then moves away?
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What condition must be met for the Doppler effect to be observed?
What condition must be met for the Doppler effect to be observed?
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What is created when an object moves faster than the speed of sound?
What is created when an object moves faster than the speed of sound?
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Which type of interference do noise-canceling headphones utilize?
Which type of interference do noise-canceling headphones utilize?
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What is the distance between a node and an antinode in a tube closed at one end?
What is the distance between a node and an antinode in a tube closed at one end?
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What effect is primarily used to identify if something is a wave?
What effect is primarily used to identify if something is a wave?
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What frequency is referred to as the fundamental frequency in a tube closed at one end?
What frequency is referred to as the fundamental frequency in a tube closed at one end?
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How many integral multiples of the fundamental frequency correspond to resonant frequencies in a tube closed at one end?
How many integral multiples of the fundamental frequency correspond to resonant frequencies in a tube closed at one end?
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How do sound waves from an object moving faster than sound spread out?
How do sound waves from an object moving faster than sound spread out?
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What does the term 'overtones' refer to in the context of resonance?
What does the term 'overtones' refer to in the context of resonance?
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In a closed tube, which frequencies are absent and not interfering constructively?
In a closed tube, which frequencies are absent and not interfering constructively?
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What is the resulting wave pattern created by the constructive interference of sound waves in musical instruments?
What is the resulting wave pattern created by the constructive interference of sound waves in musical instruments?
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What is the relationship between the length of a tube and its wavelength when it resonates at its fundamental frequency?
What is the relationship between the length of a tube and its wavelength when it resonates at its fundamental frequency?
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When a standing wave forms in a tube closed at one end, where is the maximum displacement located?
When a standing wave forms in a tube closed at one end, where is the maximum displacement located?
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What characterizes the area inside the cone of a sonic boom?
What characterizes the area inside the cone of a sonic boom?
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What is the formula for the resonant frequencies of a tube closed at one end?
What is the formula for the resonant frequencies of a tube closed at one end?
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In terms of wave formation, what occurs at the closed end of a tube that limits displacement?
In terms of wave formation, what occurs at the closed end of a tube that limits displacement?
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What is the effect on frequency when an observer moves towards a sound source?
What is the effect on frequency when an observer moves towards a sound source?
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What happens to the frequency observed when moving away from the sound source?
What happens to the frequency observed when moving away from the sound source?
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What does the variable $v_w$ represent in the given formula for Doppler shift?
What does the variable $v_w$ represent in the given formula for Doppler shift?
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What is the purpose of the minus sign in the Doppler frequency calculation when the source is moving towards the observer?
What is the purpose of the minus sign in the Doppler frequency calculation when the source is moving towards the observer?
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If an ambulance emits a siren of frequency 800 Hz while moving towards an observer, which of the following affects the frequency received?
If an ambulance emits a siren of frequency 800 Hz while moving towards an observer, which of the following affects the frequency received?
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According to the Doppler effect, what occurs to the observed frequency as the speed of the source increases?
According to the Doppler effect, what occurs to the observed frequency as the speed of the source increases?
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What is the primary difference between phons and decibels?
What is the primary difference between phons and decibels?
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In the equation for frequency received by a stationary observer ($f_{obs} = rac{v_w}{v_w ext{ } ext{ } ± v_s} f_s$), what does $v_s$ represent?
In the equation for frequency received by a stationary observer ($f_{obs} = rac{v_w}{v_w ext{ } ext{ } ± v_s} f_s$), what does $v_s$ represent?
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For a mouse just before being dispatched by a hawk flying towards it emitting a frequency of 3500 Hz, which equation format will help in determining the frequency observed by the mouse?
For a mouse just before being dispatched by a hawk flying towards it emitting a frequency of 3500 Hz, which equation format will help in determining the frequency observed by the mouse?
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Which type of hearing loss can be mitigated by sending sound vibrations through the skull?
Which type of hearing loss can be mitigated by sending sound vibrations through the skull?
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What component of the cochlear implant converts the electrical signal into impulses for the cochlea?
What component of the cochlear implant converts the electrical signal into impulses for the cochlea?
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What is the role of the microphone in a cochlear implant system?
What is the role of the microphone in a cochlear implant system?
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How many electrodes are generally found in a cochlear implant?
How many electrodes are generally found in a cochlear implant?
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Which component of a cochlear implant processes sound frequencies?
Which component of a cochlear implant processes sound frequencies?
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What happens to the cilia in the cochlea that affects hearing?
What happens to the cilia in the cochlea that affects hearing?
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What is the primary function of a cochlear implant's electrode array?
What is the primary function of a cochlear implant's electrode array?
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Study Notes
Physics of Hearing: Introduction
- Sound is a disturbance of atoms in matter, traveling outward from its origin as a wave.
- This wave phenomenon is called sound.
- The perception of sound is hearing.
- Ultrasound has applications beyond hearing, including medical imaging and treatment.
- Sound is a wave; on an atomic scale, it's a disturbance of atoms ordered more than their thermal motions.
Sound
- Sound has applications beyond hearing (e.g., ultrasound).
- The phenomenon of sound is defined as a disturbance in matter, transmitted outward from the source.
- Sound travels as a wave. On the atomic level, sound is a disturbance of atoms, more ordered than their thermal/random motions.
Periodic Waves and Sound
- Sound, in many cases, is periodic. Atoms undergo simple harmonic motion.
- The oscillating source (like a vibrating string) transfers energy to the surrounding air mostly as thermal energy due to turbulence.
- A small portion of the source's energy compresses and expands the surrounding air, creating slightly higher and lower pressure regions.
Types of Sound Waves
- Sound in air and many fluids is longitudinal (compressions and rarefactions). Fluids lack significant shear strength.
- Sound in solids can be both transverse and longitudinal.
- Compressions (higher pressure regions) and rarefactions (lower pressure regions) propagate as longitudinal waves with the same frequency as the original source.
Intensity and Amplitude
- Sound waves lose amplitude with distance from the source.
- Wave energy disperses over greater areas.
- Energy is absorbed by objects (like the eardrum) and converted into thermal energy via air viscosity.
- Heat transfer from/to the air during compression/expansion randomizes the organized disturbance.
Sound Speed, Frequency, and Wavelength
- Sound, like all waves, has a determined speed and related properties like frequency and wavelength.
- Pitch is the perception of frequency.
- Size of musical instruments correlates to the wavelengths of sound they create. (Higher pitch, the smaller the wavelength)
- Wavelength is indirectly sensed by correlations between musical instrument size and pitch.
- Speed of sound = frequency x wavelength (vw = fλ)
Properties of Sound
- The speed of sound depends on the rigidity (or compressibility for gases) and density of the medium.
- More rigid (or less compressible) mediums lead to faster sound speeds. Sound in air (which is compressible) is slower than sound in solids.
- Earthquakes, as sound waves in the Earth's crust, exemplify how sound speed depends on the rigidity (or stiffness) of the transmitting medium.
- The speed of sound in air is affected by temperature (Vw= 331 m/s * √(T/273 K), where T is in Kelvin).
- Sound speed in gases related to average particle speed (Vrms = √(3kT/m)).
- The speed of sound in a medium is roughly independent of the frequency. Different frequencies travel at the same speed within a given medium.
Sound Intensity and Level
- Intensity is power per unit area carried by a wave.
- Intensity = Power / Area (I = P/A).
- The SI unit for intensity is W/m2.
- Sound intensity is related to pressure amplitude squared: I = (Δp)2 / 2ρvw , where Δp is in Pascals (Pa)
- Sound intensity levels are typically quoted in decibels (dB) which is more common than watts per square meter
- decibels are used scientifically and popularly.
- Sound intensity level (β) in decibels of a sound with intensity β(dB) = 10 log10(I/I0)), and I0 =10-12 W/m2 is the reference intensity).
Threshold and Loudness
- The lowest perceptible sound intensity for a typical human (1000 Hz) is I0 (10-12 W/m2)
- The unit Phon is used for measuring loudness perceptions.
- Phons differ from decibels because the Phon is a unit of loudness perception rather than physical intensity.
The Doppler Effect
- The Doppler effect is the change in observed frequency due to motion of either the source or the observer.
- The change in frequency due to relative motion is called a Doppler shift.
- The Doppler effect and the Doppler shift are named for Austrian physicist Christian Johann Doppler.
- The Doppler effect occurs when sound sources or observers are moving relative to a stationary medium.
Sonic Booms and Bow Wakes
- When a source moves faster than the speed of sound, it creates a sonic boom—a shockwave of constructive interference from sound waves.
- Similar to how water waves form wakes, sonic booms are a manifestation of waves (in this case sound waves) emitted from a source moving faster than their propagation speed.
Sound Interference and Resonance
- Interference is a hallmark of waves, exhibiting constructive or destructive interference.
- Sound, being a wave, exhibits interference (constructive or destructive).
- Headphones that cancel noise use destructive interference.
- Resonances, as observed in musical instruments, are due to constructive interference of specific frequencies.
Resonance in Closed and Open Tubes
- Resonances in air columns can occur in tubes closed at one end or open at both ends.
- Closed-end tubes have maximum air displacement at the open end (an antinode) and no displacement at the closed end (a node). A tube closed at one end has the fundamental resonance at λ=4L
- Open-end tubes have maximum air displacement at both ends (antinodes). Resonances or harmonics of open tubes have λ=2L
Additional problem sets (page 14) include examples that test these principles (intensity calculation, frequency calculation, speed and wavelength relationship applications)
Human Hearing
- Hearing is the perception of sound.
- Human hearing ranges from 20 Hz to 20,000 Hz.
- Sounds below 20 Hz are infrasound; these cannot be detected by the ear, though some may be sensed as vibrations, for example.
- Frequencies above 20,000 Hz are called ultrasound and are usually not perceived as sound.
- Pitch refers to the perception of frequency.
- Loudness refers to the perception of intensity.
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Description
Explore the fascinating physics behind hearing and sound in this quiz. Understand sound as a wave phenomenon and its applications, including ultrasound in medical fields. Learn about the atomic disturbances that create sound and their periodic nature.
