IEC 61094-8-2012 PDF

Full title and description

St IEC 61094-8:2012 — Measurement microphones — Part 8: Methods for determining the free-field sensitivity of working standard microphones by comparison. This international standard defines procedures for determining the free-field sensitivity of working-standard (WS) measurement microphones by comparison with laboratory-standard or other working-standard microphones that have known, traceable calibrations.

Abstract

IEC 61094-8:2012 specifies comparison-based methods and test arrangements to obtain free-field sensitivity values for working standard microphones. It covers calibration in test environments that approximate an ideal free field (for example, high-quality free-field chambers), and techniques that use post-processing or time-selective (time-gating) methods to simulate free-field conditions where direct free-field conditions are impractical. The document describes sound-source, mounting and alignment requirements, use of reference and monitor microphones, environmental corrections and uncertainty considerations necessary to produce traceable free-field microphone calibrations.

General information

• Status: Published — current (international standard).
• Publication date: 19 September 2012.
• Publisher: International Electrotechnical Commission (IEC), TC 29 (Electroacoustics).
• ICS / categories: 17.140.50 (Electroacoustics).
• Edition / version: Edition 1.0 (2012).
• Number of pages: 61 (base IEC publication).

Scope

This part of IEC 61094 applies to working standard microphones that meet the mechanical and electrical requirements of IEC 61094-4. It describes methods to determine free-field sensitivity by comparison against a laboratory standard or an appropriately calibrated working standard (calibrated according to IEC 61094-3, IEC 61094-2, IEC 61094-5, IEC 61094-6 or IEC 61094-8 itself where applicable, and taking into account factors in IEC/TS 61094-7). The scope covers direct free-field calibrations in suitably large/treated test spaces and quasi-free-field techniques (including time-selective processing) to compensate for imperfect acoustic environments. Low-frequency limitations, mounting and alignment effects, environmental corrections and uncertainty evaluation are addressed.

Key topics and requirements

• Comparison methods for free-field sensitivity determination (sequential and simultaneous measurement approaches and combinations thereof).
• Requirements for acoustic test environments that approximate a free field (free-field chambers, anechoic conditions, and acceptable performance limits).
• Use of time-selective or time-gating techniques to discriminate direct sound from reflections (quasi-free-field methods) and their limitations.
• Selection and use of reference (laboratory-standard) and monitor microphones; recommendations for matching configurations and handling of protection grids.
• Mounting, alignment and angle-of-incidence procedures, including use of mounting rods and treatment of microphone acoustic centre and diffraction effects.
• Sound-source requirements and recommendations to approximate plane progressive waves at the measurement position.
• Environmental condition corrections (temperature, static pressure, humidity) and reporting to reference environmental conditions where appropriate.
• Uncertainty assessment guidance for comparison calibrations and handling of contributions from acoustical environment, alignment, reference microphone uncertainty and processing methods.

Typical use and users

Primary users are calibration laboratories and national metrology institutes performing free-field calibrations of measurement microphones; microphone and preamplifier manufacturers establishing product sensitivity data; research laboratories and acoustical consultants who require traceable free-field microphone calibrations; and quality/control laboratories in industries where accurate acoustic measurement is required. The standard is used both to establish laboratory procedures and to document calibration results for traceability.

Related standards

IEC 61094-8 is part of the IEC 61094 series. Relevant related documents include: IEC 61094-1 (laboratory standard microphone specifications), IEC 61094-2, IEC 61094-3 (reciprocity calibration and related methods), IEC 61094-4 (working standard microphone specifications), IEC 61094-5 (pressure comparison methods for WS microphones), IEC 61094-6 (electrostatic actuator methods), and IEC/TS 61094-7 (factors and guidance referenced by other parts). ISO 26101 (free-field room performance assessment) and national/adopted versions (EN, BS, DIN, etc.) are also commonly referenced in practice.

Keywords

measurement microphone, free-field sensitivity, working standard microphone, comparison calibration, free-field chamber, time gating, time-selective methods, acoustic calibration, IEC 61094, electroacoustics, calibration uncertainty, reference microphone, mounting and alignment

FAQ

Q: What is this standard?

A: IEC 61094-8:2012 is an international standard that specifies methods for determining the free-field sensitivity of working standard measurement microphones by comparison with calibrated reference microphones.

Q: What does it cover?

A: It covers comparison-based free-field calibration techniques carried out in environments that approximate an ideal free field (for example, high-quality free-field chambers) and quasi-free-field methods that use post-processing or time-selective gating to remove reflections. It also covers sound-source and mounting requirements, environmental corrections and uncertainty assessment.

Q: Who typically uses it?

A: Calibration laboratories, national metrology institutes, microphone manufacturers, research and development acoustics groups, and acoustic test/consulting laboratories use this standard to perform traceable free-field microphone calibrations.

Q: Is it current or superseded?

A: IEC 61094-8 was published on 19 September 2012 (Edition 1.0) and is a published international standard. The IEC listing shows a stability target extending beyond 2012 (stability to 2027 for the base publication), so it is considered current as of 25 February 2026. Users should check the IEC webstore or national standards body for any amendments, corrigenda or later revisions beyond this date.

Q: Is it part of a series?

A: Yes — IEC 61094-8 is one part of the IEC 61094 series on measurement microphones. Other parts in the series cover laboratory and working standard microphone specifications, reciprocity and comparison calibration methods, electrostatic actuator techniques and informative technical guidance (for example IEC 61094-1 through IEC 61094-6 and IEC/TS 61094-7).

Q: What are the key keywords?

A: Free-field sensitivity, working standard microphone, comparison calibration, free-field chamber, time-selective measurement, calibration uncertainty, IEC 61094.