Overview
EN ISO 8253-2:2009 - "Acoustics - Audiometric test methods - Part 2: Sound field audiometry with pure‑tone and narrow‑band test signals" (CEN adoption of ISO 8253‑2:2009) defines procedures, signal characteristics and room conditions for performing reliable sound field audiometry. Its primary purpose is to ensure accurate, reproducible determination of hearing threshold levels in the frequency range 125 Hz to 8 000 Hz (extendable to 20 Hz to 16 000 Hz). The standard covers tests using pure tones, frequency‑modulated (FM) tones and narrow‑band noise presented via one or more loudspeakers. It explicitly excludes hand‑held loudspeakers and speech test signals.
Key topics and technical requirements
- Test signal characteristics: Definitions and requirements for pure tones, FM tones and narrow‑band signals, including gating, harmonic distortion limits and level control.
- Sound field definitions: Requirements for free, diffuse and quasi‑free sound fields and how room acoustics and speaker arrangement affect measurements.
- Reference points and axes: Positioning of the listener (reference point) relative to loudspeakers and reference axis for reproducible presentation.
- Ambient noise limits: Maximum permissible background noise in the test room to protect threshold accuracy.
- Calibration and measurement scales: Means and scales for equipment calibration (SPL and hearing level references), and reference thresholds under free‑field/diffuse conditions.
- Test procedures: Guidance for monaural and binaural threshold determination, testing with hearing aids, and screening audiometry procedures.
- Reporting and graphical presentation: Recommended formats for reporting results and example graphical displays (Annex A).
- Maintenance and calibration regime: Multi‑stage approach to equipment upkeep (routine listening and checks, periodic electroacoustic tests, and basic calibration tests - Stage A, B, C).
Applications and who uses it
EN ISO 8253‑2:2009 is used by:
- Audiologists and clinicians performing pediatric or behavioural sound field audiometry.
- Hearing aid dispensers and researchers measuring functional gain with worn devices.
- Clinical engineers and medical physicists responsible for audiometric room setup, calibration and quality assurance.
- Manufacturers of audiometric equipment and loudspeakers to ensure product compatibility with standardized test conditions.
- Occupational health professionals conducting hearing screening where sound field methods are appropriate.
Practical benefits include improved measurement reproducibility, comparable clinical records across facilities, and validated procedures for evaluating hearing aids and sound‑presentation setups.
Related standards
Keywords: EN ISO 8253‑2:2009, sound field audiometry, pure‑tone, narrow‑band, hearing threshold, audiometric test methods, free field, diffuse field, calibration.
