NAL-NL2
Pronunciation: N-A-L N-L-2
Also written as: NAL-NL2 — National Acoustic Laboratories Non-Linear version 2
A widely used prescriptive hearing aid fitting formula developed by the National Acoustic Laboratories that specifies target gain values across frequencies to optimise speech intelligibility.
Full Definition
NAL-NL2 (National Acoustic Laboratories Non-Linear version 2) is a second-generation prescriptive fitting algorithm that calculates frequency-specific gain and output targets for hearing aids based on an individual's audiometric profile, accounting for compression, bilateral fitting, and demographic variables such as age and gender. It aims to maximise speech intelligibility while maintaining overall loudness at a comfortable level. NAL-NL2 is one of the two dominant adult prescriptive targets used internationally, the other being DSL v5. Editors should note that the abbreviation retains the hyphen and the numeral 2 and should not be written as 'NALNL2' or 'NAL NL2'.
Usage
Usage note: The hyphen between NAL and NL2 must be preserved. When referencing prescriptive targets, editors should confirm whether NAL-NL2 or its predecessor NAL-NL1 is intended, as they produce different gain targets.
In Context
- "Hearing aid gain was verified against NAL-NL2 targets using probe-microphone real-ear measurement." — Hearing aid verification report
- "The patient's fitting was adjusted until aided speech intelligibility scores aligned with NAL-NL2 predictions." — Audiological rehabilitation plan