SPTH341: Lecture 2 The Importance of Hearing across the Lifespan

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SPTH341 Lecture 2The Importance of Hearing
across the Life-span

• Mark C. Flynn, PhD
• Department of Speech and Language Therapy

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1. Children
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The Auditory System

• In the brain the greatest amount of neural tissue
  is auditory.
• Auditory pathways are not fully developed until
  15 years.
• Therefore any loss of auditory input will result
  in delayed neurological development.

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Hearing in Children

• 30-60 of children in NZ schools fail a hearing
  test at any one time.
• 84 of children with learning difficulties have
  a significant hearing loss.
• 10 of pre-schoolers have chronic middle ear
  problems throughout the language learning years.
• Incidence of OME is increasing!

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• Hearing loss, no matter what causes it, ALWAYS
  has negative audiological/ educational
  consequences, any hearing loss (even fluid and
  wax) is catastrophic for children.

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Effect of reduced hearing levels

• Immature neural development.
• Children with a 25dB hearing loss by the time
  they are in grade 4 are on average one grade
  level behind.
• Children with a mild (30dB) hearing loss in one
  ear are 10 times more likely to fail a grade at
  school.
• 3 of children in grades 1-3 have noise induced
  deafness - rises to 22 by high school!

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Hearing impairment leads to?
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Hearing loss

• dB is a logarithmic scale, therefore
• 6dB loss - hear half as well
• 20dB loss - 10 times less hearing
• 40dB loss -100 times less hearing

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2. Older children at School
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The School

• Classrooms are an auditory verbal environment.
• We must do all we can to maximise the auditory
  environment of the children

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Hearing in Classrooms

• The hearing of the child, the acoustic
  environment, and the speech of the teacher are
  the variables NOT the constants. ? as variables
  they can and must be manipulated.

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The silly questions we ask

• Put you hand up if you did not hear what I said.
• Can you hear me?

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Guidelines

• Noise level in an empty classroom 30-35dBA
• NZ schools between 52 and 64dBA.
• Signal-to-noise level greater than 15dB
• NZ schools between 1dB and -5dB.
• RT lt 0.4s

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The problems?

• Noise
• Distance
• Reverberation
• Signal-to-Noise Ratio (SNR)

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Noise in Classrooms

• 55-75dBA of background noise (Berg, 1993).
• 4 of classrooms in WLG are quiet enough for
  typically developing children to hear clearly
  within 3m of the teacher (Blake Busby, 1994).

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Distance

• Signal can drop 6dB with every doubling in
  distance.
• 85dB at the mouth 65dB at 1 meter distance.

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Classroom seating position
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Reverberation
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Solutions

• Acoustic modifications
• Personal FM
• Sound field FM

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Toteable Sound Field
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Sound field results

• Reading performance after 7/12. 44-48 to 78
  passing grade level tests. No other difference in
  teaching practices/services.
• Five years after the introduction of sound field
  the number of students in LD programmes decreased
  by 40 (Ohio study)
• NZ Phonological awareness study significant
  improvements over the control group (Allcock,
  1999).

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A good auditory environment benefits?

• Literacy
• Phonological awareness
• Speech and language skills
• Mathematical skills
• Vocabulary and word analysis
• Gifted as well as at risk children
• Fewer teacher absences due to fatigue and
  laryngitis.

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• The research clearly demonstrates that the most
  effective tool to decrease voice problems in
  teachers and to improve the literacy of children
  is through providing a good acoustic sound signal
  - through sound field.
• Prevention is the key

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3. Hearing in adults

• 470,000 adult New Zealanders have a
  communication impairment caused by hearing loss.
• 78 audiologists and 21 hearing therapists are not
  going to service this population effectively!

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Common hearing losses in adults

• Impacted cerumen
• Otosclerosis
• Noise induced hearing loss
• Presbycusis

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Case in point

• 33 of adults with TBI have a significant hearing
  loss (Jury Flynn, 1999).
• Most likely to be unilateral - very difficult to
  identify without hearing screening.
• Would undetected hearing loss affect test results
  (esp. receptive)?

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Undetected unilateral hearing loss in TBI

• Problems with
• noise
• localisation
• position effects in intervention (esp. groups)
• telephone training!

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4. Hearing loss and age
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Adults with aphasia or dementia

• Do we know the hearing status of the adult?
• Affects assessment results (e.g. mis-diagnosis of
  Wernickes aphasia).
• Affects management strategy (e.g. understanding
  of instructions)

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Residential Care

• Many, many adults in residential care have
  significant communication problems whose primary
  aetiology is hearing impairment.
• Not assisted by hearing aids (amplify the sounds
  but these people need communication strategies).

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Nursing home study (Erber, 92)

• 59 elderly people assessed
• 13/18 of hearing aids were malfunctioning.
• 26/59 needed assistive listening device for
  telephone or TV.
• 48/59 needed clarification strategies.

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Possible activities

• Hearing screening.
• Adaptive communication assessment.
• Communication Therapy.

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Hearing impairment is often invisible but

• 10 of pre-schoolers have chronic middle ear
  problems throughout the language learning years.
  (How many of these end up in our clinics with
  language learning and later literacy problems).
• 470,000 adult New Zealanders have a
  communication impairment caused by hearing loss.

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• Hearing loss always counts, no matter what their
  cause.
• Hearing losses of any type and degree presents a
  barrier to the incidental (casual) acquisition of
  information from the environment.
• Never assume hearing is okay