Audiology - 1 Flashcards
What is psychoacoustics?
The scientific study of sound perception
What is conductive hearing loss?
A problem with the conduction of sound from air to the inner ear
What is sensori-neural hearing loss?
A problem with the cochlea and auditory nerve
What is the term for age related hearing loss?
Presbyacousis
What components of the ear does normal peripheral hearing depend upon?
The inner hair cells (for sensory transduction of basilar membrane to auditory nerve), The outer hair cells (amplify movement of the basilar membrane at low sound levels)
What nerve do the inner hair cells drive?
The auditory nerve
What type of innervation do outer hair cells have?
Efferent innervation
How many inner hair cells do afferent fibres attach to?
One
Where will low frequency sounds cause the basilar membrane to vibrate?
The apex
Where will high frequency sounds cause the basilar membrane to vibrate?
The basal end
What type of coding does the basilar membrane send to the cochlear place?
Tonotopic
What type of hearing loss does damage to the hair cells result in?
Sensori-neural hearing loss
What are the psychoacoustic concomitants of sensori-neural hearing loss?
Loss of sensitivity, Abnormal loudness growth (e.g intense sounds appear normal, less intense sounds appear inaudibly quiet), Reduction of the dynamic range, Impaired frequency selectivity
What are the effects of inner hair cell damage?
Loss of sensitivity, Reduced ability to hear spectral detail
What are the effects of outer hair cell damage?
Loss of level-dependent amplification, Loss of frequency tuning
What is meant by the term audibility?
How much of the sounds we can hear
When is intelligibility reduced?
When not all of the speech range is audible
What type of hearing losses is audibility able to provide predictions for?
Mild to moderate hearing losses
What can audibility not restore in cases of severe hearing loss?
Intelligibility
What are the effects of a reduction in dynamic range?
Quiet sounds are inaudibile, Loudness grows very rapidly with amplitude
Name a key property of auditory coding
The cochlea acts like a bank of band-pass filters (different areas process different frequencies)
Which frequencies do hearing loss typically affect?
Higher frequencies
What percentage of people in low and middle income countries are affected by hearing loss?
80%
What is the main cause of hearing loss in children?
Chronic middle ear infection
What percentage of hearing impairment is avoidable through prevention, early diagnosis and management?
50%
What percentage of early onset hearing impairment is caused by genetic factors?
More than 50%
What are the 4 classification areas of hearing disorders?
Age of onset, Site of pathology, Aetiology, Audiometric parameters (degree of impairment, frequencies affected, temporal pattern)
What might age of onset affect with regard to hearing disorders?
Development, Education, Psychosocial factors
What might site of pathology affect with regard to hearing disorders?
Management techniques, Surgery
What might aetiology affect with regard to hearing disorders?
Counselling (genetics), Management, Prevention
What might audiometric parameters affect with regard to hearing disorders?
Management, Education, Development, Psychosocial
What is it important to find out when considering age of onset?
Whether it is the age when the hearing loss was diagnosed or the age symptoms were first recognised
When can age of onset hearing loss occur?
Pre or post lingual (before / after the development of language)
What type of hearing loss occurs when the site of pathology is the outer / middle ear?
Conductive
What type of hearing loss occurs when the site of pathology is the cochlea + VIII nerve?
Sensori-neural
What type of hearing loss occurs when the site of pathology is the higher auditory pathways and temporal lobe?
Central auditory processing disorders
Is conductive hearing loss usually temporary or permenant?
Temporary
If a person has conductive hearing loss will they be able to hear if the sound reaches the cochlea?
Yes
Can conductive hearing loss be treated medically or surgically?
Often yes
Is sensori-neural hearing loss temporary or permenant?
Permenant
Why is sensori-nerual hearing loss permenant?
Because structures of the cochlea and/or auditory nerve are damaged, stopping transmission of sound to the brain
Can sensori-neural hearing loss be treated medically or surgically?
No
What is a central auditory processing disorder?
When sound reaches the brain but cannot be interpreted
What types of hearing loss can central auditory processing disorders occur with?
Conductive and sensori-neural
What is ototoxicity?
Drugs that can damage the ear
What is meant by ‘syndromic hearing loss’?
The presence of syndromes which can affect hearing loss through alterations to facial and ear structures
Name a chromosomal abnormality that can affect hearing
Down’s Syndrome
Why can people with Down’s Syndrome affected by hearing loss?
They have narrow ear canals and high prevelances of middle ear problems
What does OME stand for?
Otitis Media with Effusion
What is meant by an otocraniofacial syndrome?
A syndrome which affects the cranium, face and ears
What is Treacher-Collins Syndrome?
A congenital disorder characterised by craniofacial deformities (absent cheekbones, downward slanting eyes)
What kind of hearing loss is someone with Treacher-Collins Syndrome likely to experience?
Conductive
What are non-syndromic causes of hearing loss?
Factors which are not related to syndromes but cause hearing loss
Name some examples of non-syndromic hearing loss in the outer ear
Foreign bodies, ear wax
Name an example of non-syndromic hearing loss in the middle ear
OME, Otosclerosis, Cholesteatoma
What is Otosclerosis?
Fusion of the ossicles (stapes become attached to the oval window)
What is a possible treatment for Otosclerosis?
Stapedectomy
What type of hearing loss does Otosclerosis usually cause?
Conductive (can result in permenant hearing loss)
What is Cholesteatoma?
Invasive growth in the middle ear / mastoid process (rare in western countries)
What can sensori-neural hearing loss be secondary to?
Head injury, local trauma, systemic disease (renal, metabolic, liver)
What is the current model for sensori-neural hearing loss?
Genetic + environmental
What is the ratio of children born with permenant childhood hearing impairment (PCHI)?
1 in 1000
What percentage of permenant childhood hearing impairment is acquired, progressive or late onset?
16%
What percentage of permenant childhood hearing impairment is as a result of meningitis?
5%
What percentage of sensori-neural hearing loss is genetic?
50% +
What percentage of sensori-neural hearing loss is syndromic?
30%
What is the most common gene for non-syndromic recessive and sporadic sensori-neural hearing loss?
Connexin 26
Name some syndromes associated with sensori-neural hearing loss
Usher’s Syndrome, Waardenburg’s Syndrome, Jervell and Lange-Nielson Syndrome
What is a characteristic physical feature of Waardenburg’s Syndrome?
A white forelock and bright blue eyes
What are some of the pre- and peri-natal problems that can cause sensori-neural hearing loss?
Prematurity, Hypoxia, Low birth weight, Severe neonatal jaundice, Maternal alcohol
What are some of the infections associated with sensori-neural hearing loss?
Rubella, Syphillis, Menningitis, Measles, Mumps
If a child has suffered from Meningitis what must they been screened for?
Hearing changes
What is one of the leading health problems in industrialised countries?
Noise
What are the risk factors associated with noise induced hearing loss?
Intensity and duration of exposure, Individual susceptibility (genetic), Medications (ototoxic)
What does Meniere’s Syndrome affect?
The cohlea
What are some of the associated risk factors with Meniere’s Syndrome?
Stress, Diet, Migrane association
What is Acoustic Neuroma?
Tumour on the auditory nerve (usually benign)
What is the estimated prevelance of central auditory processing disorder?
5% of school-aged children
What are the characteristics of central auditory processing disorders?
Poor recognition, discrimination, separation, grouping and ordering of non-speech sounds
