STRC Research

hypa-db-bands

2 min read

Clinical dB-band grounding log

WHO 2021 classification

  • Retrieved: 2026-08-21
  • Exact query: site:who.int World Report on Hearing hearing loss grades 20 35 50 65 80 dB
  • Index/path: web search → https://iris.who.int/bitstream/handle/10665/339913/9789240020481-eng.pdf
  • Source/edition/pages: World Health Organization, World Report on Hearing, first edition, 2021, ISBN 978-92-4-002048-1, Table 1.3, p. 38.
  • Verbatim passage: “Normal hearing Less than 20 dB; Mild hearing loss 20 to <35 dB; Moderate hearing loss 35 to <50 dB.”
  • Weight: STATES CURRENT WHO EPIDEMIOLOGICAL BANDS. The script’s 25/40/55/70/90 boundaries do not match this table.
  • Bridging derivation: none. Relabeling the script to WHO would require replacing bands; that would be a separate sourced classification edit, not a repair of the OHC-to-threshold calibration.

ASHA 2023 information sheet / Clark 1981 system

  • Retrieved: 2026-08-21
  • Exact query: site:asha.org public hearing loss degrees 26-40 41-55 56-70 71-90
  • Index/path: web search and PDF open → https://www.asha.org/siteassets/ais/ais-type-degree-and-configuration-of-hearing-loss.pdf, lines 56-74 / PDF p. 1.
  • Source/edition/pages: American Speech-Language-Hearing Association, Audiology Information Series, Type, Degree, and Configuration of Hearing Loss, ©2023, p. 1; table attributes Clark JG (1981), ASHA 23:493-500.
  • Verbatim passage: “Normal -10 to 15; Slight 16 to 25; Mild 26 to 40; Moderate 41 to 55.”
  • Weight: STATES ONE COMMONLY USED CLASSIFICATION. The executable code collapses ASHA/Clark Normal and Slight into “Normal ⇐25,” while the later bands approximately follow this system; calling the result “WHO/ASHA” is inaccurate.
  • Bridging derivation: none needed for the mismatch. This classification concerns dB HL hearing-loss ranges; it does not validate ABR dB units or the transfer-function calibration.

Unresolved operational thresholds

  • RESPONDER_THRESHOLD_DB = 20: Lv 2024 reports observed 40-57 dB average ABR reductions but its primary endpoint was dose-limiting toxicity; the retrieved abstract does not define a >=20 dB responder rule.
  • FUNCTIONAL_THRESHOLD_DB = 55: 55 dB is an ASHA/Clark band edge, but neither WHO nor ASHA states that ⇐55 dB means “functional hearing.” That interpretation is a separate unsourced claim.

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