Hearing Threshold Level
Also written as: HTL — Hearing Threshold Level
The intensity, expressed in decibels (dB HL), at which a pure tone is just audible to a listener 50% of the time, measured relative to established audiometric norms.
Full Definition
Hearing threshold level (HTL) is the standard measure recorded on an audiogram, expressed in dB HL, where 0 dB HL represents the average threshold of normal-hearing young adults for a given frequency. An individual's HTL at each test frequency reflects the degree of hearing loss: thresholds of 0–25 dB HL are generally considered within normal limits for adults, with increasing values indicating progressively greater loss. HTL is distinct from sound pressure level (dB SPL), which is a physical measure not normalized to human hearing. Editors working on audiometric reports must ensure that dB values are appropriately labeled as 'HL' or 'SPL' and that the abbreviation 'HTL' is expanded on first use.
Usage
Usage note: Always include the reference quantity suffix: 'dB HL', not simply 'dB'. Do not conflate with dB SPL (sound pressure level).
In Context
- "The hearing threshold level at 4000 Hz was recorded as 65 dB HL in the right ear." — Audiological assessment report
- "Editors should verify that all dB values in the audiogram table are labeled as dB HL rather than dB SPL." — Technical editing checklist