Physiology III - Bone Conduction

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Questions and Answers

What effect does closing or blocking the external auditory canal have on low-frequency sounds?

It amplifies high-frequency sounds.

It amplifies low-frequency sounds. (correct)

It prevents sound vibrations from entering.

It has no effect on sound transmission.

What are bone conduction earphones primarily used for?

To amplify high-frequency sound waves.

To provide a rich sound experience.

To transmit sound through traditional auditory pathways.

To enjoy audio without affecting environmental awareness. (correct)

What is the primary advantage of bone conduction earphones over traditional earphones?

They allow users to hear environmental sounds. (correct)

They are more comfortable to wear.

They are more affordable.

They offer better sound quality.

How does cartilage conduction differ from bone conduction?

CC relies on vibration of the cartilage in the external ear. Signup and view all the answers

Which of the following sound transmission mechanisms was discovered by Hosoi in 2004?

Cartilage conduction (CC) Signup and view all the answers

What must be considered an inherent trade-off of using bone conduction earphones?

Lower sound quality at lower frequencies. Signup and view all the answers

What is one characteristic of vibrations transmitted through bone conduction?

They are subject to occlusion effect. Signup and view all the answers

Which feature makes bone conduction earphones potentially preferable for athletes?

They allow hearing surrounding traffic. Signup and view all the answers

What is the average gap calculated from the total of 150 when divided by 4?

38 dB Signup and view all the answers

What type of hearing loss is typically indicated in the case of the 55-year-old female teacher?

Sensorineural hearing loss Signup and view all the answers

Which hearing aids are recommended for the 55-year-old female teacher in the case study?

BTE or ITE hearing aids Signup and view all the answers

What is one limitation of using hearing protection devices?

Difficulty in communicating Signup and view all the answers

According to the World Health Organization, what was the increase in estimated hearing loss from 1995 to 2004?

From 120 million to 250 million Signup and view all the answers

What does the acronym NIOSH stand for?

National Institute for Occupational Safety and Health Signup and view all the answers

What does the occlusion effect refer to?

Interference with communication when using hearing protection Signup and view all the answers

What does the term 'air-bone gap' refer to?

Discrepancy between air conduction and bone conduction thresholds Signup and view all the answers

What is the primary function of the tympanic membrane in the process of sound transmission?

To amplify pressure by focusing sound onto the oval window Signup and view all the answers

How much sound pressure gain is typically provided by the inner ear at 1000 Hz?

25 dB Signup and view all the answers

What role do the ossicles play in sound transmission?

They increase mechanical force between the tympanic membrane and the oval window Signup and view all the answers

At what frequency range does the sound pressure gain diminish by approximately 6 dB per octave?

After 1000 Hz Signup and view all the answers

Which type of hearing aids is custom-molded to fit directly into the ear canal?

In-the-ear (ITE) Signup and view all the answers

What significant feature do modern hearing aids offer beyond simple sound amplification?

Decomposition of sounds into frequency channels for customization Signup and view all the answers

Which statement about the process of sound traveling from air to the inner ear is correct?

An impedance mismatch occurs, requiring compensatory mechanisms in the inner ear Signup and view all the answers

What is a common intervention for hearing loss not related to middle ear problems?

Use of hearing aids Signup and view all the answers

What is the average threshold when 20 dB, 25 dB, 30 dB, and 35 dB are added together?

28 dB Signup and view all the answers

What is the formula for calculating the Air-Bone Gap (ABG)?

Air conduction threshold minus bone conduction threshold Signup and view all the answers

What is the result of the calculation at 2000 Hz, where the air conduction threshold is 75 dB and the bone conduction threshold is 30 dB?

45 dB Signup and view all the answers

How do you calculate the average Air-Bone Gap (ABG) from the differences at each frequency?

Add the differences and divide by 4 Signup and view all the answers

For the frequencies of 500 Hz to 4000 Hz, what is the overall sum of the differences when air conduction thresholds are 50, 60, 75, and 80 dB, and bone conduction thresholds are 20, 25, 30, and 40 dB?

150 dB Signup and view all the answers

What would be the Air-Bone Gap (ABG) at 1000 Hz given the air conduction threshold is 60 dB and the bone conduction threshold is 25 dB?

35 dB Signup and view all the answers

If the round-up of the average threshold of four values is 28, what could the values have been?

20, 25, 30, 35 Signup and view all the answers

What is the difference in dB at 4000 Hz when the air conduction threshold is 80 dB and the bone conduction threshold is 40 dB?

40 dB Signup and view all the answers

What effect does wearing hearing protectors have on voice perception for many people?

Creates discomfort leading to removal Signup and view all the answers

Which type of bone conduction is less affected by conductive hearing loss?

Bone conduction threshold Signup and view all the answers

Which of the following is NOT a solution to reduce the occlusion effect in hearing aids?

Adding more insulation Signup and view all the answers

In terms of bone conduction threshold sensitivity, which placement yields lower sensitivity?

Forehead placement Signup and view all the answers

How can the occlusion effect impact the use of hearing aids?

It decreases total sound volume and can distort sound perception Signup and view all the answers

Which mechanism is NOT one of the four primary mechanisms contributing to bone conduction?

Transcutaneous bone conduction Signup and view all the answers

What type of hearing aid is considered more powerful?

Percutaneous bone conduction hearing aids Signup and view all the answers

Which frequency range is primarily impacted by the occlusion effect?

Below 1000 Hz Signup and view all the answers

What can be a consequence of not addressing the occlusion effect in hearing aids?

Potential users may avoid using hearing aids altogether Signup and view all the answers

Which of the following factors influence bone conduction thresholds?

Static force and placement Signup and view all the answers

What is the primary function of devices that utilize bone conduction technology?

To transmit sound signals to the inner ear via vibration of the skull Signup and view all the answers

Which of the following conditions makes a patient eligible for the ADHEAR device?

BC thresholds below 25 dB in the 500 to 4000 Hz range Signup and view all the answers

Which device is suitable for patients with bone conduction thresholds below 55 dB in the 500 Hz to 3000 Hz range?

The Osia from Cochlear Signup and view all the answers

What is the maximum air-bone gap (ABG) for patients suitable for the Ponto device?

Above 30 dB Signup and view all the answers

How is the Pure Tone Average (PTA) calculated for bone conduction thresholds?

By summing the thresholds at specified frequencies and dividing by 4 Signup and view all the answers

Which device is designed to provide a non-surgical option for bone conduction hearing?

The ADHEAR Signup and view all the answers

What is the threshold range for the Bonebridge device?

Below 45 dB in the 500 Hz to 4000 Hz range Signup and view all the answers

Which of the following statements about the ADHEAR device is correct?

It uses adhesive technology for comfort. Signup and view all the answers

What is a common criterion for selecting transcutaneous bone conduction devices?

BC PTA of 0.5-4 kHz ≤ 55 dB Signup and view all the answers

Study Notes

Auditory Physiology: Bone Conduction

Bone conduction refers to sound transmission through bone to the inner ear.
Different pathways of sound transmission exist before reaching the cochlea; one travels through air conduction while the other travels through direct bone conduction. A third pathway is indirect bone conduction.
The pinna and ear canal aid in sound localization in the vertical plane and provide natural sound amplification, especially in the mid-range frequencies of 2000-7000 Hz.
Sound waves move down the ear canal composed of external cartilaginous and inner bony portion.
The tympanic membrane (eardrum) marks the beginning of the middle ear. This membrane is sensitive to sound vibrations.
The ossicles (malleus, incus, and stapes) in the middle ear act as a lever system, amplifying the mechanical force from the tympanic membrane to the oval window. The stapes pushes vibrations through to the oval window of the cochlea.
The cochlea, a spiral-shaped structure, contains distinct fluids (perilymph and endolymph). Movement of the stapes at the oval window creates waves in the perilymph.
The resulting wave in the basilar membrane interacts with the tectorial membrane bending stereocilia on hair cells generating neural signals that propagate to the auditory nerve.
The middle ear addresses the impedance mismatch between air and liquid media in the inner ear. The tympanic membrane focuses sound from a larger area onto a smaller oval window amplifying pressure. The ossicles increase the mechanical force between the tympanic membrane and the oval window.
The inner ear converts acoustic energy into mechanical energy.
The transmission of sound through the skull.
The mechanics and behavior of bone conduction differ due to frequency.
- At lower frequencies (150-400 Hz): skull behaves as rigid body motion.
- Between 400-1000 Hz: mass-spring system and large parts of the skull move in phase.
- Between 1-2 kHz: wave transmission becomes dominant. Skull-base and vault have different properties.
The skull transitions from mass-spring-like behavior to wave transmission between 1-2 kHz.
Four mechanisms contribute to bone conduction:
- Compressional bone conduction
- Distortional bone conduction
- Inertial (ossicular-lag) bone conduction
- Osseotympanic bone conduction
Factors influencing bone conduction thresholds include static force and the type of vibrator. -Static force > 4N and the type of vibrator does not significantly influence BC measurements. -Forehead overall lower sensitivity compared to the mastoid.
Masking of the nontest ear is required during bone conduction testing. -Transcranial attenuation between ears is 0-15dB when using mastoid as site of stimulation. No attenuation when using forehead for stimulation. Masking is important to ensure only one ear is being stimulated.
Middle ear pathologies impact bone conduction hearing.
Common forms of bone conduction hearing devices and how they work.

Occlusion Effect

Occlusion effect describes sound amplification due to the impedance change of the ear canal when the canal is closed.
When the ear canal is blocked (by earphones, earplugs, or earmolds), sound waves are trapped and the impedance of the ear canal increases, increasing sound pressure at the eardrum.
Different methodologies use for calculation, such as subjective methodologies which used to measure ear canal attenuation threshold (unoccluded threshold) and (occluded threshold). Subjective methodology is not the best methodology since it can be affected by physiological noise and the methodology underestimates the occlusion effect.
Impact on hearing aids. This can cause auditory discomfort due to altered voice perception.
Solutions to reduce the occlusion effects via changes in hearing aid design are possible. Alternative designs such as open domes, shortening vent lengths, and or increasing vent diameters can help reduce this effect.
The impact of occlusion effect on hearing protection. Workers in noisy environments do not always use hearing protection which has implications for auditory health.

Candidacy Case Studies

Case study example 1:
- 55-year-old female teacher exhibiting sensorineural hearing loss and difficulty understanding speech in noise. Recommendation: BTE or ITE hearing aids.
Case study example 2:
- 35-year-old male construction worker with conductive hearing loss and history of otitis media. Recommendation: non-surgical (likely ADHEAR if BC thresholds are low) bone conduction hearing aids.
Case study example 3: -60-year-old female with otosclerosis and complains of difficulty in hearing in various environment (both ears). Mixed hearing loss. Recommendation: Percutaneous or Transcutaneous bone conduction hearing aids.
Case study example 4: -40-year-old male musician with single-sided deafness, and struggles with localization. Recommendation: Percutaneous bone conduction hearing aid (on the deaf side).
Case study example 5: -68-year-old female with age-related hearing loss and severe allergic reactions to earmolds. Recommendation: Bone conduction hearing aids, and if BC thresholds are below 25 dB, ADHEAR would be a surgical alternative.

Bone-Anchored Hearing Aids (BAHA)

BAHA hearing devices bypass the ear canal and transmit sound to the cochlea via bone conduction.
Useful for patients with recurring ear infections, or malformations of the external auditory canal.

Cochlear Implants

Cochlear implants may be considered for SSD patients with good cochlear health in the deaf ear who do not benefit from CROS or bone conduction aids.

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Description

Explore the fascinating mechanisms of auditory physiology, focusing on bone conduction and sound transmission pathways. This quiz delves into the role of the ear's structures, including the tympanic membrane and cochlea, and their functions in sound localization and amplification. Test your knowledge of how sound waves travel through different mediums to reach the inner ear.