IEC 60268-21:2018

Overview

IEC 60268-21:2018 defines standardized acoustical (output-based) measurements for sound system equipment. The method applies to electro-acoustical transducers and both passive and active sound systems - for example loudspeakers, TV-sets, multi‑media devices, personal portable audio devices, automotive sound systems and professional equipment. The standard specifies physical measurement procedures that assess the transfer behaviour between an arbitrary analogue or digital input and the acoustical output in the near and far field. It covers operation in both small‑signal and large‑signal domains and allows inclusion of application-specific acoustical boundary conditions (e.g., car interiors). It does not cover perceptual or cognitive evaluation of sound quality.

Key topics and technical requirements

• Measurement scope: Transfer between input signal and acoustic output at defined evaluation points (near/far field).
• Test signals: Defined signal types such as sinusoidal chirps, single‑ and two‑tone signals, multi‑tone and broadband/noise, Hann bursts and impulsive signals for different analyses.
• Acoustical environment: Procedures for free‑field, half‑space, diffuse field, simulated and target‑application conditions.
• Positioning & geometry: Reference plane, reference point/axis, evaluation distance and orientation vectors for repeatable measurements.
• Key metrics: Sound‑pressure output (SPL), rated maximum SPL, short‑ and long‑term maximum levels, SPL in frequency bands, mean SPL and frequency response of the fundamental component.
• Directional characteristics: 3D direct sound field measurements, extrapolated near/far‑field data, directivity factor/gain, directivity index and acoustic output power.
• Measurement quality: Requirements for measurement equipment, uncertainty analysis, preconditioning, mounting and rated ambient conditions (temperature, humidity).
• Additional parameters: Effective frequency range, internal latency, amplitude compression (time‑varying and at maximum input).

Applications and users

IEC 60268-21 is essential for:

• Audio manufacturers (design verification, datasheets, product comparison)
• Test laboratories and QA teams (type approval, production testing, verification of rated SPL/frequency response)
• R&D and acoustic engineers (system tuning, loudspeaker characterization, networked audio devices)
• Automotive and consumer electronics teams needing target‑application (cabin) measurements.

Typical uses include publishing verified SPL/frequency response data, quantifying directivity and acoustic output power, and validating performance under real‑world boundary conditions.

Related standards

• Part of the IEC 60268 series on sound system equipment; consult other parts of the series for electrical measurements, terminology and system‑level requirements.
• Use alongside laboratory and acoustics guides for measurement uncertainty and environment control.