ISO 10494:2018

Overview

ISO 10494:2018 - Turbines and turbine sets: Measurement of emitted airborne noise - Engineering/survey method specifies standardized methods to measure the airborne noise emitted by turbines and turbine sets under steady-state operating conditions. The standard defines how to measure sound pressure levels on a measurement surface that envelops the source and how to calculate the sound power level (A‑weighted and in octave/one‑third‑octave bands). It is applicable to stationary power‑plant and industrial turbines, ship and offshore installations, and road/railway vehicle installations - but excludes gas turbines in aircraft applications.

Key topics and technical requirements

• Measurement surface and reference surface: Requirements for defining an enveloping surface around the turbine or turbine set (only the part above the floor and inside a continuous surface).
• Acoustic environment: Criteria for test environments, background noise limits, wind effects and qualification procedures (Annex A). Methods include engineering (grade 2) and survey (grade 3) approaches.
• Instrumentation and calibration: Requirements for microphones, analyzers and calibration procedures to obtain reliable A‑weighted and spectral data.
• Microphone locations and sampling: Guidance on the number and location of microphone positions, including additional positions for surface and directivity assessment.
• Data processing and corrections: Procedures for correcting background noise and environment effects, calculation of surface-averaged sound pressure level, sound power level, and directivity index/factor. Limits for corrections: grade 2 (background ≤ 1.3 dB, environment ≤ 4 dB) and grade 3 (background ≤ 3 dB, environment ≤ 7 dB).
• Operational conditions: Applies only to steady‑state operation; excludes transients (start‑up/shut‑down).
• Reporting and documentation: Mandatory test report content and recorded information (instrumentation, operating conditions, acoustical data).

Practical applications and users

ISO 10494:2018 is used by:

• Turbine manufacturers for performance and design verification (noise budgeting).
• Acoustic test laboratories and field test engineers conducting on‑siteMeasurements.
• Power plant, marine and offshore operators for compliance, environmental assessment and noise mitigation planning.
• Acoustic consultants and procurement teams specifying noise limits for installations. Practical uses include comparing turbine noise performance, estimating expected sound pressure levels in surrounding environments, verifying compliance with contractual noise limits, and guiding noise control engineering.

Related standards

• ISO 3744:2010 (sound power determination - engineering methods)
• ISO 3746:2010 (survey methods)
• Other ISO series on sound power and room methods referenced in ISO 10494

Keywords: ISO 10494:2018, turbines noise measurement, sound power level, A-weighted, measurement surface, acoustic environment, turbine sets, engineering survey method.