Overview
EN ISO 9295:2015 - "Acoustics - Determination of high-frequency sound power levels emitted by machinery and equipment (ISO 9295:2015)" specifies standardized test methods to measure high-frequency sound power levels in the octave band centered at 16 kHz (covering approximately 11.2 kHz to 22.4 kHz). The standard defines four complementary measurement methods (three using reverberation test rooms and one using a free field over a reflecting plane) and sets requirements for test conditions, instrumentation, calibration, data reporting and measurement uncertainty. Measured levels are not frequency-weighted; the primary objective is to determine sound power and tone frequencies present in the 16 kHz octave band.
Key topics and requirements
- Scope and purpose: Measurement of high-frequency sound power from machinery and equipment, including broadband noise and discrete tones (e.g., switching power supplies, high-speed printing noise).
- Four measurement methods:
- Three reverberation-room based methods (including one using measured reverberation time, one using calculated air absorption, and one using a reference sound source).
- One method using a free field over a reflecting plane (hemi-anechoic conditions).
- Test conditions: Installation and operating conditions for equipment under test are those specified in ISO 3741 or ISO 3744, as applicable.
- Measurement controls:
- Meteorological and environmental conditions
- Instrumentation and calibration procedures
- Microphone and equipment placement and orientation
- Reverberation time and room constant measurements
- Calculation steps including air absorption (Annex A) and conversion to sound power level
- Quality and reporting: Requirements for measurement uncertainty estimation and detailed information to record and report (equipment, acoustic environment, instrumentation, acoustical data).
Applications
- Product noise assessment for machinery that emits high-frequency noise (industrial equipment, medical devices, electronic equipment).
- Compliance testing and certification where high-frequency emission data are required.
- Research & development and design validation to reduce high-frequency noise or mitigate discrete tones.
- Workplace noise evaluation and environmental noise studies involving ultrasonic or near-ultrasonic components.
Who uses this standard
- Acoustic consultants and test laboratories
- Manufacturers of machinery, electronic and medical equipment
- R&D and product design engineers
- Regulatory bodies and conformity assessment organizations concerned with noise emissions
Related standards
- ISO 3741 - laboratory determination of sound power (reverberation room)
- ISO 3744 - field and laboratory methods for sound power determination
- ISO 9295 is prepared by ISO/TC 43 (Acoustics) and complements the above standards for the 16 kHz octave band.
Keywords: EN ISO 9295:2015, high-frequency sound power levels, 16 kHz octave band, reverberation test room, free field over a reflecting plane, ISO 3741, ISO 3744, acoustics testing.
