IEC 61094-5:2016

Overview

IEC 61094-5:2016 is an international standard published by the International Electrotechnical Commission (IEC) that establishes methods for the pressure calibration of working standard microphones by comparison techniques. This standard applies to working standard microphones with removable protection grids conforming to IEC 61094-4, as well as laboratory standard microphones meeting IEC 61094-1 specifications.

The document outlines procedures to determine the pressure sensitivity of measurement microphones through comparison with either a laboratory standard microphone or another working standard microphone with a known sensitivity over the relevant frequency range. This second edition, published in 2016, supersedes the first edition from 2001 and includes a technical revision with expanded guidance on uncertainty components, updated corrections, and provisions for calibration using driven shield configurations.

Key Topics

• Scope and Applicability: Focuses on working and laboratory standard microphones, providing calibration methods fundamental to ensuring measurement accuracy in electroacoustic applications.

• Calibration Methods:

  • Comparison Techniques: Procedures for comparing the pressure sensitivity of a test microphone against a reference microphone with known sensitivity.
  • Simultaneous vs Sequential Excitation: Principles for both techniques that involve either exciting microphones simultaneously or sequentially to measure output voltages accurately.

• Environmental and Physical Factors:

  • Details on factors influencing pressure sensitivity such as microphone pressure equalization, polarizing voltage, shield configurations, and pressure distribution across diaphragms.
  • Importance of maintaining reference environmental conditions during calibration to ensure consistent and reproducible results.

• Calibration Uncertainty:

  • Comprehensive treatment of uncertainty components including sensitivity of the reference microphone, output measurement variations, acoustic impedance effects, microphone separation distance, and configuration during calibration.
  • Guidelines for calculating and reporting combined and expanded uncertainties related to microphone pressure calibration.

• Practical Equipment Examples:

  • Informative annexes provide examples of various couplers and jigs used for simultaneous and sequential excitation methods at different frequency ranges.
  • Illustrations and tables assist users in selecting appropriate calibration hardware setups tailored to specific microphone types.

• Terminology and Definitions: Clear definitions for terms such as test microphone, reference microphone, monitor microphone, and coupler to establish a common understanding essential for proper application.

Applications

IEC 61094-5:2016 plays a crucial role in industries and fields where accurate measurement of sound pressure is essential, including:

• Acoustic Measurement Laboratories: Ensuring traceable and standardized calibration of microphones used in precision electroacoustic testing.
• Audio Equipment Manufacturing: Calibration of microphones for product development and quality assurance processes.
• Environmental Noise Monitoring: Calibration of microphones deployed in field measurements to maintain consistency and reliability.
• Research and Development: Supporting development of new microphone technologies requiring validated sensitivity references.
• Compliance Testing: Assisting regulatory testing with measurement microphones calibrated according to international standards for legal and technical conformity.

Related Standards

To fully implement the calibration methods described in IEC 61094-5, it is essential to refer to related IEC standards within the IEC 61094 series:

• IEC 61094-1: Specifies technical requirements for laboratory standard microphones, including performance and design specifications essential to calibration accuracy.

• IEC 61094-4: Defines specifications for working standard microphones, which are used more routinely in calibration with removable protection grids.

Additional complementary standards include IEC 61094-2, which details alternative comparison methods that may be used beyond the scope of Part 5.

Summary

IEC 61094-5:2016 provides the electroacoustic community with rigorous, internationally recognized methods for the pressure calibration of measurement microphones by comparison. Its focus on accuracy, uncertainty assessment, and practical calibration setups ensures reliable determination of microphone pressure sensitivity. Adherence to this standard supports consistency, traceability, and quality in acoustic measurements across diverse applications worldwide.

Keywords: IEC 61094-5, pressure calibration, working standard microphones, laboratory standard microphones, electroacoustics, microphone sensitivity, comparison calibration, microphone uncertainty, acoustic measurement standards.