EN ISO 389-8:2004 PDF

Overview

EN ISO 389-8:2004 (ISO 389-8:2004) defines reference equivalent threshold sound pressure levels (RETSPLs) for pure tones delivered by a specified model of circumaural earphone (SENNHEISER HDA 200). The standard covers RETSPLs in the frequency range 125 Hz to 8 kHz for the calibration of air-conduction audiometers and provides supporting data (attenuation and free-field correction figures) in informative annexes. Values are derived from multi-laboratory measurements on otologically normal subjects and are intended to establish a common calibration reference (“reference zero”) for audiometric equipment.

Key Topics

• Scope and purpose: Establish RETSPLs for pure-tone audiometry using the HDA 200 circumaural earphone (125 Hz–8 kHz).
• Reference coupling: Calibration is specified for an ear simulator and adapter per IEC 60318-1 and IEC 60318-2 (Figure 1).
• RETSPL values: Tabulated RETSPLs (in dB re 20 μPa) are given for standard audiometric frequencies (e.g., 1 000 Hz ≈ 5.5 dB; 4 000 Hz ≈ 9.5 dB; 8 000 Hz ≈ 17.5 dB). Full values are presented in Table 1 of the standard.
• Environmental and mechanical conditions: Calibration is recommended at 21 °C to 25 °C; headband force for the HDA 200 is specified as 10.0 N ± 1.0 N with defined positioning dimensions.
• Annex B - sound attenuation: Provides mean attenuation data for the HDA 200 across octave bands (useful for assessing background-noise protection).
• Annex C - free-field corrections: Gives correction figures to convert coupler measurements to free-field equivalent outputs (applicable to speech audiometer calibration).
• Derivation and traceability: RETSPLs are based on results from five independent investigations (see Annex A and Bibliography).

Applications

• Calibration of clinical and occupational audiometers using circumaural earphones (SENNHEISER HDA 200).
• Reference for audiology clinics, calibration laboratories, device manufacturers and test houses to ensure consistent pure-tone threshold measurements.
• Use in hearing conservation programs, regulatory compliance, and research where standardized audiometric calibration is required.
• Basis for producing free-field-equivalent outputs for speech audiometry and for assessing earphone noise attenuation characteristics.

Related Standards

• ISO 389-1 (supra-aural earphones)
• ISO/TR 389-5 (extended high-frequency RETSPLs)
• IEC 60318-1, IEC 60318-2 (ear simulators/adapters)
• IEC 60645-2 (speech audiometers)

Keywords: EN ISO 389-8:2004, ISO 389-8, RETSPL, circumaural earphones, SENNHEISER HDA 200, audiometer calibration, audiometric equipment calibration, IEC 60318-1, free-field correction.