TSH.8 Hearing Impairment and Hearing Aids

These flashcards cover key concepts, terms, and details from the lecture on hearing impairment and hearing aids.

What is auditory localisation?

The ability to determine the direction from which sound originates using both monaural and binaural cues.

What are the two cues used for auditory localisation?

Monaural cues and binaural cues.

How does the human ear determine the direction of sound?

By using interaural time differences (ITD) and interaural level differences (ILD).

What is interaural time difference (ITD)?

The difference in the time it takes for sound to reach each ear.

What causes interaural level differences (ILD)?

The presence of the head creating an acoustic shadow that affects the intensity of sound reaching each ear.

At what frequency do interaural level differences become effective?

Above about 1000 Hz.

Why is ITD ineffective above 4000 Hz?

The difference in phase between sound waves becomes poorly defined.

What role does the pinna play in sound localisation?

It amplifies sound differently from above and below, helping to identify elevation.

What is audiometry?

A procedure to measure hearing function and hearing loss using an audiometer.

What unit is hearing function measured in?

Decibel Hearing Level (dBHL).

How is a hearing threshold defined?

The sound intensity at which a person first detects a tone.

What is the threshold of audibility in dBHL?

0 dBHL.

How is an audiogram produced?

By plotting the intensity at which sounds are just heard against different frequencies.

What does an upside-down y-axis in an audiogram represent?

The louder the tone needed to be heard, the further down the symbol appears, indicating hearing loss.

What is conductive hearing loss?

Hearing loss caused by disorders in the outer or middle ear preventing sound from reaching the inner ear.

What can cause conductive hearing loss?

Infections, wax buildup, foreign objects, fluid in the middle ear, eardrum damage, ossicle dislocation, or tumors.

What is bone conduction?

The conduction of sound directly into the cochlea through vibrations in the skull.

What is sensorineural hearing loss?

Hearing loss resulting from problems in the cochlea or auditory nerve.

What distinguishes air conduction tests from bone conduction tests?

Air conduction tests assess the entire auditory pathway, while bone conduction tests focus only on the cochlea.

What do the symbols x and o represent in an audiogram?

Air conduction markers.

What is presbycusis?

Age-related sensorineural hearing loss due to degeneration of inner ear nerves and sensory cells.

What frequency range is most affected by presbycusis?

High frequencies.

What are common causes of sensorineural hearing loss?

Injury, noise exposure, viral infections, ototoxic drugs, meningitis, stroke, high fever, tumors, heredity, diabetes.

What is mixed hearing loss?

Hearing loss resulting from both conductive and sensorineural components.

What is an example symbol for bone conduction in an audiogram?

[ or ] or < or >.

What indicates that a hearing aid might be necessary?

An audiogram showing greater than 55 dBHL loss in the 100-3000 Hz frequency range.

What is the typical conversational volume?

Approximately 60 dB.

How do hearing aids work?

They deliver sound via the ear canal and act as amplifiers.

What is the function of cochlear implants?

To bypass damaged hair cells and directly stimulate the auditory nerve.

What does digital electronics enable in hearing aids?

The ability to tailor frequency response exactly to the individual's needs.

What is a key design consideration for hearing aids?

Avoiding sounds above the threshold of pain, which is about 120-130 dB.

What are the components involved in hearing loss measurement?

Air conduction and bone conduction testing.

Do both air and bone conduction tests need to be performed for accurate diagnosis?

Yes, to identify the specific source of hearing loss.

What can be inferred if there is a significant difference between air and bone conduction results?

A conductive hearing loss may be present.

What types of headphones have gained popularity for facilitating bone conduction?

Bone conduction headphones.

What should be done to maximize the effectiveness of hearing aids?

Personalization to fit the unique needs of the individual.

What is the impact of an acoustic shadow on sound?

It decreases the intensity of sound reaching one ear compared to the other.

At what frequencies is interaural time difference most effective?

Around 1000 Hz and below.

In what way does the pinna assist with sound localisation?

By amplifying sounds from different elevations.

What determines the loss of hearing as depicted on an audiogram?

The further down the symbols on the audiogram indicate the greater the hearing loss.

Why are audiometers important in hearing tests?

They generate the sounds needed to create an audiogram.

What does the term 'decibel' represent in hearing measurement?

A logarithmic unit used to express the intensity of sound.

What testing is done to explore neural hearing loss specifically?

Bone conduction testing using small transducers.

Why might hearing aids be indicated for individuals with high-frequency hearing loss?

Because voices and sounds in conversation typically fall within the frequency range of 100-3000 Hz.

What should be considered when designing a hearing aid?

The individual’s specific hearing loss profile and comfort with sound intensity.