audiometry

• what are the 5 hearing thresholds called and their ranges in Audiomtery:

  • Normal hearing: can hear quiet sounds of less than 20dB
  • Mild hearing loss: hearing loss between 20 – 40dB
  • Moderate hearing loss: hearing loss between 41 – 70dB
  • Severe hearing loss: hearing loss between 71 – 95dB
  • Profound hearing loss: hearing loss over 95dB
• air-bone gap (ABG) is a difference between air-conduction and bone-conduction audiometric thresholds.

  • found in patients with conductive (CHL) or mixed (MHL) hearing loss generally attributed to outer- and/or middle-ear diseases such as otitis externa, tm perforation, interruption or fixation of the ossicular chain, and chronic suppurative otitis media.4

  Typically an air-bone gap is considered if there is a difference of greater than 10dB at a given frequency.
• How is tympanometry done?

  1. audiologist performs otoscopy - easier to see ear canal, eardrum and middle ear
  2. insert the probe part of tympanometer. The probe will have a soft end and create an airtight seal in ear canal
  3. The probe will send air into your ear while emitting a low tone
  4. may feel pressure building in ear before your ears “pop"
  5. microphone on probe will record how your eardrum moves in response to the sound and air pressure.
  6. The tympanometer will create a graph called a tympanogram that shows how your eardrum moved.
• The peak on a tympanogram provides important information about the compliance, or flexibility, of the tympanic membrane (eardrum) and the middle ear system. It represents the point of maximum movement of the eardrum in response to changes in air pressure and sounds applied to the ear canal during the tympanometry test.
• outcomes on a tympanometry:

  1. Normal peak: In a healthy ear, the peak of the tympanogram typically occurs near the middle of the graph and is well-defined. This indicates normal middle ear function with appropriate movement of the eardrum.
  2. Absent peak: If there is no discernible peak on the tympanogram, it may indicate a significant problem with middle ear function. This could be due to factors such as a perforated eardrum, fluid buildup in the middle ear (effusion), or a blockage in the ear canal.
• outcomes on tympanometry:

  1. Flat peak: A flat or shallow peak may suggest reduced compliance of the eardrum and middle ear system. This could be caused by conditions such as otitis media with effusion (fluid in the middle ear), eustachian tube dysfunction, or scarring of the tympanic membrane.
  2. Peak shifted to the left: A peak shifted to the left on the tympanogram may indicate stiffness of the middle ear system, possibly due to conditions such as ossicular chain fixation or otosclerosis.
• outcomes on a tympanometry:

  1. Peak shifted to the right: Conversely, a peak shifted to the right may suggest increased compliance of the middle ear system, which could occur in conditions such as ossicular discontinuity or flaccid eardrum.
• examples of hearing support:

  • Hearing aids (Behind the ear, in the ear, in the canal, completely in canal, body worn)

  • Bone anchored devices (soft band (want to avoid surgery) or surgical implants)

  • Middle ear implants (vibrates ossicles)

  • Cochlear Implants (wire which stimulates hair cells)

  • Other aids – Bluetooth aids, hearing loops, visual alarm systems

  • Adjustments – work, telephone, face when speaking
• what does audiogram indicate:

  Normal audiogram (above 20dB in all frequencies)

  
• what does this audiogram indicate:

  Sensorineural hearing loss (right ear): no air-bone gap present

  Sensorineural hearing loss refers to hearing loss due to damage to the structures of the inner ear (cochlea) or cochlear nerve.

  Common causes of sensorineural hearing loss include:

  • Sudden sensorineural hearing loss (SSHL): the underlying aetiology remains unclear but is thought to relate to possible vascular, viral, inflammatory or immune-mediated causes
  • Noise-induced hearing loss
  • Presbyacusis
  • Vestibular schwannoma

  
• what does this audiogram indicate:

  Conductive hearing loss (right ear): air-bone gap present

  Conductive hearing loss refers to hearing loss due to impaired sound transmission through the outer and middle ear.  

  Common causes of conductive hearing loss include:

  • Any obstruction to the ear canal (e.g. wax, foreign body, furuncle, oedema)
  • Perforation of tympanic membrane
  • Fluid in the middle ear (e.g. glue ear, otitis media)
  • Any disruption of ossicles (e.g. trauma)

  
• what does this audiogram indicate:

  Presbyacusis (age-related hearing loss) 

  The pathophysiology of age-related hearing loss (ARHL), or presbycusis, involves a complex interplay between environmental and genetic factors.6 These include noise exposure, genetic predisposition, cell damage and neural degeneration.

  Presbycusis is characterised by bilateral hearing loss above 2000Hz. On a standard audiogram, presbycusis appears as an overall down-sloping line representing impaired hearing at higher frequency sounds.5

  Presbyacusis is classically bilateral and symmetrical.

  
• what does the diagram indicate:

  Noise-induced hearing loss (sensorineural hearing loss with a notch at 4000 Hz)

  Noise-induced hearing loss is typically characterised by a notch on the audiogram at 4000 Hz.

  
• what does the diagram indicate:

  Meniere’s disease (right ear)

  Meniere’s disease is typically characterised by low-frequency sensorineural hearing loss.

  
• what is meniere's triad

  Meniere’s disease presents a triad of vertigo, tinnitus and hearing loss.
• what does this diagram indicate:

  Otosclerosis (right ear)

  Otosclerosis is pathologically characterised by abnormal bony remodelling, which includes bone resorption, new bone deposition, and vascular proliferation in the temporal bone. 7

  Otosclerosis is characterised by conductive hearing loss with loss in bone conduction at 2000 Hz (referred to as Carhart’s notch).