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Hearing Exam > week 1 > Flashcards

week 1 Flashcards

hearing introduction

1
Q

What is sound?

A

Sound is defined as the movement of a disturbance through an elastic medium without permanent displacement of the particle.

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2
Q

what are soundwaves?

A

Physical disturbance in air pressure, arising from a vibrating source. Air molecules compress and rarify in a pattern, depending on the nature of the source vibrations.

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3
Q

How is hearing measured?

•

A

Pure tone = periodic, equal vibrations, at regular intervals.
Complex sound = comprised of several pure tones.
Aperiodic sound = variations in wave form. Many natural sounds are aperiodic.

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4
Q

what is the decibel scale?

A

> Measures sound pressure
Strength of a sound compared to a reference intensity.
- Usually interested in the smallest sound perceptible by the human ear as reference intensity in measuring human hearing.
Logarithmic scale
Numerous scales
- Commonly use dB HL (hearing level) or dB HTL (hearing threshold level)

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5
Q

what is the hearing process from sound waves to neural impulses?

A

Sound waves: a wave of compression and rarefaction, by which sound is propagated in an elastic medium such as air.
Transduction: In the auditory system, sound vibrations (mechanical energy) are transduced into electrical energy by hair cells in the inner ear. Sound vibrations from an object cause vibrations in air molecules, which in turn, vibrate the ear drum.

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6
Q

How does sound travel from the environment to the afferent pathway?

A
  • Air conduction: vibrations travel through the middle ear to the cochlea via air.
  • Bone conduction: vibrations travel to the cochlea via the skull bones.
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7
Q

what structures are essential in sound travel?

A

> Outer ear: pinna and external auditory meatus (EAM)
Middle ear: Tympanic membrane and Ossicles (malleus, incus, stapes OR hammer, anvil, stirrup)
Inner ear is essential: skull bones (usually temporal bone) and fluid in the inner ear

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8
Q

why is the outer ear essential in sound travel?

A
  • Sound pressure waves are funneled by the Pinna (auricle) through the ear canal (external auditory meatus).
  • EAM conducts sound waves to tympanic membrane.
  • Pressure waves strike the tympanic membrane (TM) causing it to vibrate.
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9
Q

why is the middle ear essential in sound travel?

A
  • Tympanic membrane vibrates in response to sound.

- Ossicles (malleus, incus, stapes OR hammer, anvil, stirrup) conduct vibrations to oval window.

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10
Q

why is the inner ear essential in sound travel?

A

> Sounds vibrate skull bones (usually temporal bone)

>Vibrations of fluid in the inner ear create electric potential to transduce sound wave into neural impulses.

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11
Q

The afferent pathway

A

Cochlear and vestibular branches of CNVIII join at the internal auditory canal.
• Afferent impulses travel up CNVIII, through the brainstem to the auditory cortex.
> Decussation of impulses at cochlear nucleus.
> Direct left-right communication also occurs at:
- Superior olivary nucleus (brainstem)
- Inferior colliculus (mid-brain).

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12
Q

CNS control of The hearing process: Auditory cortex

A

• Superior temporal gyrus (temporal lobe).
• Binaural hearing results from decussation of afferent input at various levels of the pathway.
• Primary auditory cortex processes:
> Temporal order of sounds.
>Frequency combinations.
• Secondary and tertiary auditory cortices process:
> language
> Motor production of language and processing of syntax in Broca’s area
> Wernicke’s area processes speech perception.

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13
Q

What constitutes normal hearing?

A

Normal hearing: hearing thresholds of ≥25dB in both ears.

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14
Q

What constitutes hearing loss?

A

Hearing loss: pure tone average in the better ear below 25dB at frequencies 500Hz, 1000Hz, 2000Hz and 4000Hz

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15
Q

What constitutes disabling hearing loss?

A

> Adults – loss >40dB in the better ear.

> Children – loss >30dB in the better ear

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16
Q

4 Hearing loss facts.

A
  1. ~5% of the world’s population experience disabling hearing loss.
  2. ↑ 1/3 of adults >65.
  3. ~50% of cases of hearing loss are preventable.
  4. Worldwide production of hearing aids meets <10% of demand/need.
17
Q

what are the classification for hearing loss?

A
  • Congenital vs acquired
  • Conductive vs sensorineural vs mixed
  • Pre-lingual vs post-lingual
18
Q

Peripheral auditory processing

A
  • Hearing ability
  • Pre-linguistic
  • Perceive and attend to sounds
  • Perceive differences in sounds
  • Detect differences in pitch
  • May be inconsistent: “not an all or nothing phenomenon” (p. 29)
19
Q

what are the classification for hearing loss?

A
  • Congenital vs acquired
  • Conductive vs sensorineural vs mixed
  • Pre-lingual vs post-lingual
20
Q

Types of hearing loss (Doyle, 1998)

A

Conductive:
Sensorineural:
Mixed

21
Q

Conductive hearing loss

A

> “Changes to the mechanics of the external or middle ear” (p. 34)
Caused by irregularities in outer and/or middle ear changing the conduction of soundwaves.
Inner ear intact.

22
Q

sensorineural hearing loss

A

> Damage to cochlea and/or auditory nerve.

> Frequency and intensity of incoming soundwaves not correctly coded and/or transduced and/or transmitted.

23
Q

mixed hearing loss

A

> Features of both types of hearing loss (with conduction better).

24
Q

What causes of conductive hearing loss do you know of?

A 
> Otitis media.
> Foreign bodies.
> Otosclerosis.
> Wax occlusion.
> Cleft palate.
>Tympanic membrane perforation. 
> Cancers.
> Cholesteatoma
> Syndromes
> Medications/ Substance abuse
> Noise
> Aging
> Genetics
25
Q

What causes of sensorineural hearing loss do you know of?

A 
> Noise exposure.
> Genetically inherited.
> Meningitis. 
> Ototoxic drugs. 
> Maternal rubella. 
> Head injury.
> Etc.
26
Q

Timing of onset of hearing loss (pre vs. post lingual)

A

Pre-lingual:
> Prior to the acquisition of spoken communication
> Usually prior to 3 years
Post-lingual:
> After competence in spoken language is achieved.

27
Q

Factors affecting developmental needs and outcomes

A

• Age of identification / acquisition / amplification
>Pre-lingual
>Post-lingual
• Age and nature of intervention provided
• Severity of loss
• When clients use Cochlea Implant, nonverbal intelligence, implant characteristics and oral-aural communication predict accuracy of speech sound production.
• Pattern of loss
• Associated difficulties
> Cognition
>Anatomical issues (e.g., affecting decisions around implantation of CI or BAHA).

28
Q

Prevalence of Sensorineural Hearing Loss in Adulthood

A

> One of the most common chronic health problems
Estimated at 1 in 10
Strongly associated with functional decline and depression
(Loss of >25dB in better ear)
Prevalence of 16.6% in SA (inc. presbycusis)

29
Q

effects of Sensorineural Hearing Loss in Adulthood

A 
>  Exacerbated by: 
- Competing demands for attention (Auditory,  Visual and Cognitive) 
- Reduction in cues to scaffold comprehension (Visual and Gestural)
>  Psychological implications:
-  Shame, embarrassment 
- Denial
-  Loss of autonomy 
-  Depression
- Anxiety
- Frustration
30
Q

causes of Sensorineural Hearing Loss in Adulthood

A
  • Noise-induced
  • . presbycusis
  • meniere’s disease
  • Head trauma
31
Q

noise induced Sensorineural Hearing Loss in Adulthood

A

> NIHL excludes cases of acoustic trauma.
- Long-term occupational or social exposure
_ Gradual onset
Outcome dependent on:
intensity
duration
frequency; and
susceptibility of the person
- Damage more likely to outer hair cells |
- “4K notch” observed in industrial NIHL

32
Q

presbycusis induced Sensorineural Hearing Loss in Adulthood

A 
> Age-related degeneration 
> Bilateral, progressive 
> Onset from ~50 years of age 
> More rapid for men than women 
> 40% of western populations >75
33
Q

meniere’s disease induced Sensorineural Hearing Loss in Adulthood

A

> Affects the membranous inner ear → balance and hearing symptoms.
Chronic, episodic:
- vertigo with disequilibrium + horizontal rotatory nystagmus.
- hearing loss (may be fluctuating)
- aural fullness and/or tinnitus
Prevalence: 17 – 46/100,000, F:M=1.3:1
Paediatric cases reported but onset usually in forties and fifties.
Familial trend

34
Q

Head trauma induced Sensorineural Hearing Loss in Adulthood

A 
> Overt fracture of temporal bone 
- Cochlea fracture 
> May co-occur with conductive loss
-  Fracture of ossicles
- Tympanic membrane rupture 
> Facial nerve may be affected (20 – 40% of cases)

Hearing Exam (3 decks)

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