What is ISO 389‑7- Reference threshold of hearing for the calibration of audiometric equipment about?
ISO 389 discusses acoustics for the reference zero for the calibration of audiometric equipment. ISO 389‑7 is an international standard on reference threshold of hearing under free-field and diffuse-field listening conditions for the calibration of audiometric equipment to minimize any measurement uncertainty
ISO 389‑7 is the seventh part of a multi-part series that specifies a reference threshold of hearing for the calibration of audiometric equipment used under the following conditions.
- The sound field in the absence of the listener consists of either a free progressive plane wave (free field) or a diffuse sound field, as specified in ISO 8253-2. In the case of a free field, the source of sound is directly in front of the listener (frontal incidence)
- The sound signals are pure (sinusoidal) tones in the case of free-field conditions and one-third octave bands of (white or pink) noise in the case of diffuse-field conditions
- The sound pressure level is measured in the absence of the listener at the position where the center of the listener’s head would be
- Listening is binaural
Note: The threshold data differ from the audiometric zero specified in ISO 389-1, ISO 389-2, ISO 389-5, and ISO 389-8, since the latter refers to monaural listening through earphones with sound pressure levels referred to specified couplers and ear simulators. Direct comparison between the data in the parts of ISO 389 mentioned above and in this document is therefore not appropriate.
Who is ISO 389‑7- Reference threshold of hearing for the calibration of audiometric equipment for?
ISO 389‑7 on the reference threshold of hearing for the calibration of audiometric equipment is useful for:
- Acoustic engineers
- Audiologists
- Audiometric equipment manufactures
- Audiometric equipment testing laboratories/test personnel
Why should you use ISO 389‑7- Reference threshold of hearing for the calibration of audiometric equipment?
In some audiological applications, the test signals are delivered using loudspeakers, either in a free sound field or in a diffuse sound field. ISO 389‑7 specifies the reference zero for the calibration of audiometric equipment used for sound field audiometry.
ISO 389‑7 provides you with specifications that help to ensure that the hearing level that is indicated by the audiometer complies with the strict values of the manufacturer's specific references for hearing thresholds.
ISO 389‑7 enables you to enhance the performance and accuracy of audiometric equipment and to produce equipment that has global acceptance in the market.
What is changed since the last update?
BS EN ISO 389‑7:2019 supersedes ISO 389-7:2005 which is withdrawn. BS EN ISO 389‑7:2019 has made some technical changes with respect to ISO 389-7:2005. These include:
- The reference thresholds of hearing at 20 Hz under the conditions of free-field and diffuse-field listening and the reference threshold of hearing at 18 000 Hz under the condition of free-field listening were recalculated using additional experimental data
- The bibliography was updated
