Podcast
Questions and Answers
Which part of the outer ear primarily functions in collecting and amplifying sound?
Which part of the outer ear primarily functions in collecting and amplifying sound?
What is the length of the auditory canal?
What is the length of the auditory canal?
Which of the following is NOT a function of the auditory canal?
Which of the following is NOT a function of the auditory canal?
What is the fundamental frequency of the standing wave in the ear canal if its length is 2.5 cm and the velocity of sound in air is approximately 330 m/s?
What is the fundamental frequency of the standing wave in the ear canal if its length is 2.5 cm and the velocity of sound in air is approximately 330 m/s?
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At which range is the ear most sensitive to frequencies?
At which range is the ear most sensitive to frequencies?
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What type of wave is produced in the ear canal?
What type of wave is produced in the ear canal?
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What percentage of the incoming intensity is reflected at the tympanic membrane?
What percentage of the incoming intensity is reflected at the tympanic membrane?
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What main function does the tympanic membrane serve?
What main function does the tympanic membrane serve?
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Where in the outer ear are standing waves produced?
Where in the outer ear are standing waves produced?
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Which statement best describes the impedance matching at the tympanic membrane?
Which statement best describes the impedance matching at the tympanic membrane?
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Study Notes
The Outer Ear
- Collects and directs sound waves towards the tympanic membrane
- Consists of the pinna, auditory canal, and the tympanic membrane
Pinna
- Collects sound and directs it towards the ear
- Acts as a funnel to amplify sound
- Adds directional information to the sound
Auditory Canal
- A tube running from the outer ear to the middle ear
- Approximately 2.5 cm in length and 0.7 cm in diameter
- Functions include:
- Protecting the eardrum from shocks
- Preventing harmful items from entering the ear canal
- Amplifying sound by acting as a resonator
- Producing standing waves
Standing Waves
- A closed cylindrical air column produces resonant standing waves at a fundamental frequency and odd harmonics
- The length of the column (L) and wavelength (λ) are related as: L = n(λ/4), where n = 1, 3, 5, 7,...
- The velocity of sound in air is approximately 330 m/s
- The fundamental frequency of the standing wave in the ear canal is given by: F1 = v/(4L) Hz
Standing Waves in the Ear Canal
- Produced by the reflection of sound waves at the eardrum
- Frequencies of the standing waves are given by: fn = n(v/(4L)) Hz, where n = 1, 3, 5, 7,...
- The ear is most sensitive to frequencies in the range of 2000-10000 Hz, with best sensitivity in the region of 2000-4000 Hz
Tympanic (Eardrum) Membrane
- A cone-shaped piece of skin, 10mm in width, separating the outer ear from the middle ear
- Very sensitive, responding to even the slightest pressure variation
- Main function is to transfer sound from the air into the ossicles of the middle ear
Reflection and Transmission at the Tympanic Membrane
- The acoustical signal travels along the ear canal and hits the eardrum, causing partial reflection and transmission of the signal
- To optimize hearing sensitivity, reflection should be minimized and transmission maximized
- Reflected intensity (Iref) is 99% of the incoming intensity (Iin)
- Transmitted intensity (Itrans) is 1% of the incoming intensity (Iin)
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Description
Learn about the structure and functions of the outer ear, including the pinna, auditory canal, and tympanic membrane. Understand how they work together to collect and direct sound waves.
