ISO 389-6:2007

Overview

ISO 389-6:2007 - Acoustics - Reference zero for the calibration of audiometric equipment - Part 6 defines reference hearing threshold levels for short‑duration test signals used in audiometric calibration. Short‑duration signals (clicks and tone‑bursts, <200 ms) are common in evoked‑response audiometry (e.g., auditory brainstem responses, electrocochleography) and transient otoacoustic emission testing. The standard provides median reference values and measurement concepts to promote consistent, comparable calibration and reporting of audiometric results.

Key topics and requirements

• Scope and signal definitions: Defines short‑duration signals, clicks, tone‑bursts, condensation/rarefaction polarity, alternating polarity, and reference pulse/tone‑burst waveforms (as specified in IEC 60645‑3).
• Reference metrics: Introduces RETSPL/RETVFL (reference equivalent threshold sound pressure/vibratory force levels), RTSPL (free‑field thresholds), and peak‑to‑peak equivalent levels (peRETSPL, peRETVFL, peRTSPL) for short signals.
• Recommended reference values: Provides tables of recommended peRETSPL and peRETVFL for common transducers (supra‑aural and circumaural earphones, insert earphones, loudspeakers, bone vibrators) and typical test conditions (e.g., click trains at 20 Hz).
• Calibration conditions: Specifies the dependence of thresholds on transducer type, ear simulator or coupler (IEC 60318 series), repetition rate and pulse polarity.
• Informative annexes: Annex A gives correction values for different repetition rates and single‑click vs. click‑train comparisons; Annex B reports head‑and‑torso simulator findings; Annex C documents the experimental basis for the reference levels.

Practical applications and users

Who uses ISO 389-6:2007 and why:

• Clinical audiology and diagnostic labs: Calibrate equipment used in evoked response audiometry and otoacoustic emission testing to ensure accurate thresholds.
• Medical device manufacturers: Design and validate audiometers, transducers and bone vibrators against standardized reference thresholds.
• Calibration laboratories and metrology institutes: Perform traceable calibrations of earphones, insert transducers, loudspeakers and bone vibrators using specified ear simulators and couplers.
• Researchers and standards bodies: Compare auditory threshold data across studies and develop interoperable test protocols.

Practical value:

• Ensures consistency and comparability of short‑duration signal measurements across devices and sites.
• Supplies correction factors (repetition rate, single vs. train clicks) that improve measurement accuracy.
• Supports clinical interpretation and regulatory compliance for audiometric devices.

Related standards

• ISO 389‑1 (pure‑tone RETSPLs)
• ISO 389 series (other parts addressing bone vibrators, free‑field, high frequencies)
• IEC 60645‑3 (audiometric test signals - short duration)
• IEC 60318‑1/4/6 (ear and coupler simulators)
• IEC 61094‑1 (measurement microphones)

Keywords: ISO 389‑6:2007, acoustics, audiometric equipment calibration, short‑duration signals, clicks, tone‑bursts, peRETSPL, RETSPL, evoked response audiometry.