dB HL
Also written as: dB HL — Decibels Hearing Level
Decibels hearing level; the unit used in clinical audiometry to express hearing thresholds relative to the average threshold of normal-hearing young adults, as standardized in ISO 8253-1.
Full Definition
dB HL (decibels hearing level) is the reference scale used on audiograms and in clinical audiological reports to express the intensity of sounds relative to the standardized normal hearing threshold (0 dB HL). It differs from dB SPL (sound pressure level), which is referenced to 20 µPa. On an audiogram, 0 dB HL is placed at the top of the vertical axis, and hearing loss is represented by thresholds plotted below (i.e., at higher numerical values). Editors must ensure that dB HL and dB SPL are not used interchangeably and that the correct reference scale is specified in methods sections and equipment descriptions.
Usage
Usage note: Always write as 'dB HL' with a space between the numeral and the unit (e.g., 40 dB HL, not 40dBHL). Distinguish from dB SPL (sound pressure level) and dB nHL (normalized hearing level, used in ABR testing).
In Context
- "Thresholds poorer than 25 dB HL at any frequency are generally considered indicative of hearing loss in adults." — Clinical audiology protocol
- "The manuscript inconsistently used 'dB HL' and 'dB SPL'; the editor flagged this as requiring clarification from the authors." — Manuscript peer review