Overview - EN ISO 11904-2:2021 (Manikin technique)
EN ISO 11904-2:2021, "Acoustics - Determination of sound immission from sound sources placed close to the ear - Part 2: Technique using a manikin", specifies measurement methods for assessing sound exposure from sources located close to the ear using a manikin (head and torso simulator) equipped with ear simulators and microphones. Measurements made on the manikin are converted to free-field or diffuse-field related equivalent continuous A‑weighted sound pressure levels (L Aeq). The standard covers the frequency range 20 Hz to 10 kHz and is intended for equipment testing and workplace noise assessments where direct environmental measurements do not represent ear exposure.
Key topics and technical requirements
- Measurement principle: use of a calibrated manikin with ear simulators to record sound pressure levels at the ear position and convert those values to free-field or diffuse-field equivalents.
- Instrumentation: requirements for manikins (head and torso simulators), ear simulators, microphones, and filters consistent with relevant IEC/ITU references.
- Calibration & checks: procedures for calibration and verification of manikin microphone responses and system stability.
- Frequency range: applicable from 20 Hz to 10 kHz (for >10 kHz, ISO 11904-1 is referenced).
- Signal processing: guidance on octave/fractional-octave filters and A‑weighting and summation to produce L Aeq values.
- Reporting: required content for test reports (see Clause 7).
- Uncertainty: informative Annex A (sources of measurement uncertainty) and Annex B (example uncertainty analysis) to support reliable interpretation.
Normative references include IEC 61260 (filters), IEC 61672‑1 (sound level meters) and ITU‑T P.58 (head and torso simulator).
Applications and users
This standard is practical for:
- Acoustics and test laboratories performing headphone, earphone, headset and hearing-protector audio tests.
- Manufacturers of personal audio equipment and communication-enabled hearing protection validating product exposure levels.
- Occupational hygienists and safety professionals assessing employee exposure to close-to-ear sources (e.g., headsets, in-ear monitors, nail guns).
- Standards bodies and compliance testers needing a repeatable manikin-based technique to report free-field or diffuse-field related L Aeq.
Typical applications: equipment certification, workplace noise assessments where ear-coupled sources dominate, combined exposure evaluations (earpiece + ambient field).
Related standards
- ISO 11904-1 - MIRE technique (microphones in real ears), complementary method covering up to 16 kHz.
- IEC 61260, IEC 61672‑1, ITU‑T P.58 - referenced for filters, sound level meters and head & torso simulator specifications.
Keywords: EN ISO 11904-2:2021, manikin technique, acoustics, sound immission, free-field related, diffuse-field related, A-weighted, ear simulators, headphone testing, workplace noise assessment.