What is the audiogram

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fonetika201510-21The audiogram is a graphical representation of hearing ability. It is the result of a pure tone audiometry (PTA) in a form of a curve of a hearing threshold for air and bone conduction in the frequency scale. During the hearing test, it is checked for different frequency ranges and volume. The audiogram is the most common representation of the test results issued to patients during initial hearing diagnosis. On this basis, the type and degree of hearing loss can be usually determined. It is also the basis for choosing a hearing aid or cochlear implant.

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AUDIOGRAM SHOULD ALWAYS PRESENT TWO CURVES:

– air conduction hearing threshold (right ear O, left ear X)

– bone conduction hearing threshold (right ear <, left ear > )

audiometria_tonalna_krzywe
The result of PTA is placed on the audiometric grid, which is the audiogram

NOTE The presence of two curves: air and bone conduction ensures a correct diagnosis. If there is only one curve one the audiogram (unless it’s not a study in pure tone), the test is incomplete. 

Hearing loss classification

In Poland, there are two standards: WHO (1997) and BIAP. The first standard is used frequently, the second, due to the stricter criteria, used frequently to assess children’s hearing. It’s important to remember that existence of standards does not obligate everyone to apply it. Hence, sometimes you can meet assessment rate of hearing loss. WHO standard (1997) is now also used by ENT doctors, according to the guidelines of the National Health Fund. Hearing loss is determined from the average of the hearing threshold for three or four frequencies: 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz.

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fonetika201510-13
The basis of the audiometry is the otoscopy test

Hearing loss classification by BIAP:

  • 0–20 dB – standard hearing
  • 21–40 dB – slight hearing loss
  • 41–70 dB – moderate hearing loss
  • 71–90 dB – severe hearing loss
  • over 91 dB – profound hearing loss

 

Hearing loss classification by WHO:

  • No hearing loss (less than 25 dB): no or very little hearing loss, full hearing of a whisper
  • Small hearing loss (26 to 40dB): the ability to hear and repeat words spoken in a normal voice from a distance of 1m. In this case, it is recommended to consult ENT doctor. The possible need for a hearing aid
  • Moderate hearing loss (41- 60dB): the ability to hear and repeat words spoken with raised voice at a distance of 1m. In this case, hearing aid is usually recommended
  • Large hearing loss (61- 80 dB): the ability to hear certain words, shouted to the better ear In this case hearing aid is required
  • Profound hearing loss

Based on Śli­wiń­ska– Kowal­ska M., Kry­te­ria oceny sły­sze­nia u osób wyko­nu­ją­cych pracę wyma­ga­jącą dobrej spraw­no­ści słu­chu, “Oto­la­ryn­go­lo­gia” 2013 nr 12(3);Criteria for evaluation of hearing in people who work requires good listening skills, Otolaryngology 2013, issue 12