{
  "note": "Every third-party number on /hearing-test/ comes from this file. Each block names its source, the URL it was fetched from and the fetch date (RULE 1152(a)). The page reads this file at run time; nothing here is remembered.",
  "degreeBands": {
    "source": "Olusanya BO, Davis AC, Hoffman HJ. Hearing loss grades and the International classification of functioning, disability and health. Bulletin of the World Health Organization 2019;97(10):725-728, Table 2: grades recommended by the Global Burden of Disease Expert Group on Hearing Loss. doi:10.2471/BLT.19.230367",
    "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6796665/",
    "fetched": "2026-10-26",
    "basis": "Pure-tone average of 500, 1000, 2000 and 4000 Hz, in the better ear.",
    "bands": [
      { "name": "Normal hearing", "min": -10, "max": 19.9, "quiet": "Excellent or good hearing" },
      { "name": "Mild", "min": 20, "max": 34.9, "quiet": "Does not have problems hearing what is said", "noisy": "May have real difficulty following or taking part in a conversation" },
      { "name": "Moderate", "min": 35, "max": 49.9, "quiet": "May have difficulty hearing a normal voice", "noisy": "Has difficulty hearing and taking part in conversation" },
      { "name": "Moderately severe", "min": 50, "max": 64.9, "quiet": "Can hear loud speech", "noisy": "Has great difficulty hearing and taking part in conversation" },
      { "name": "Severe", "min": 65, "max": 79.9, "quiet": "Can hear loud speech directly in one's ear", "noisy": "Has very great difficulty hearing and taking part in conversation" },
      { "name": "Profound", "min": 80, "max": 94.9, "quiet": "Has great difficulty hearing", "noisy": "Cannot hear any speech" },
      { "name": "Complete or total", "min": 95, "max": 120, "quiet": "Profoundly deaf, hears no speech or loud sounds", "noisy": "Cannot hear any speech or sound" }
    ],
    "unilateral": { "betterBelow": 20, "worseAtLeast": 35, "text": "< 20.0 dB HL in the better ear, 35.0 dB HL or greater in the worse ear" }
  },
  "symbols": {
    "source": "American Speech-Language-Hearing Association, Guidelines for Audiometric Symbols (Committee on Audiologic Evaluation, 1990), Table 1 and section 'The Audiogram'",
    "url": "https://www.asha.org/policy/gl1990-00006/",
    "fetched": "2026-10-26",
    "airRight": "O",
    "airLeft": "X",
    "boneRight": "<",
    "boneLeft": ">",
    "quote": "One octave on the frequency scale shall be equivalent in span to 20 dB on the HL scale. The range on the abscissa should include frequencies from 125 Hz to 8000 Hz while the range on the ordinate should include levels from -10dB to 120 dB HL",
    "lines": "a solid line should connect the air conduction threshold ... In cases of an air-bone gap, a dashed line can be used to connect bone conduction thresholds",
    "octavePx20dB": true,
    "freqMin": 125,
    "freqMax": 8000,
    "dbMin": -10,
    "dbMax": 120
  },
  "colours": {
    "source": "American Speech-Language-Hearing Association, The Audiogram (public page)",
    "url": "https://www.asha.org/public/hearing/audiogram/",
    "fetched": "2026-10-26",
    "quote": "Red O symbols typically represent the right ear, and blue X symbols represent the left ear.",
    "right": "red",
    "left": "blue"
  },
  "procedure": {
    "source": "British Society of Audiology, Recommended Procedure: Pure-tone air-conduction and bone-conduction threshold audiometry with and without masking (2018), sections 6.4 and 6.7",
    "url": "https://www.thebsa.org.uk/wp-content/uploads/2024/01/Recommended-Procedure-Pure-Tone-Audiometry-2018.pdf",
    "fetched": "2026-10-26",
    "order": [1000, 2000, 4000, 8000, 500, 250],
    "stepDown": 10,
    "stepUp": 5,
    "familiarisationStepUp": 10,
    "quote": "Continue to decrease the level by 10 dB and increase by 5 dB until the subject responds at the same level on two out of two, three or four (i.e. 50 % or more) responses on the ascent. This is the hearing threshold level."
  },
  "ageLine": {
    "included": false,
    "reason": "No freely readable primary source we could fetch gives the highest frequency people of a given age can hear in a form this page could compare with. The open studies report hearing thresholds in calibrated dB HL at fixed extended high frequencies (for example 9 to 20 kHz), and whether a tone is heard depends on its level, which this page does not know. The standard tables of hearing by age (ISO 7029) are not free to read. So the page gives no age line.",
    "checked": [
      "https://pmc.ncbi.nlm.nih.gov/articles/PMC8394048/",
      "https://pmc.ncbi.nlm.nih.gov/articles/PMC9244329/",
      "https://pmc.ncbi.nlm.nih.gov/articles/PMC11674001/"
    ],
    "fetched": "2026-10-26"
  }
}