Acoustics — Declared noise emission values of information technology and telecommunications equipment
1Key Takeaways
This document is applicable to information technology and telecommunications equipment. It specifies: a) for a batch of equipment, the method for determining the following values: — the declared mean A-weighted sound power level, LWA,m; — the declared mean A-weighted emission sound pressure level, LpA,m; — the stati…
2Expert Interpretation
This in-depth analysis of the ISO 9296:2017 standard's technical requirements for noise declarations for information technology and communications equipment includes sound power level determination methods, declared value calculation procedures, verification procedures, and standardized presentation requirements. This guide is suitable for equipment manufacturers, testing organizations, and purchasers conducting noise compliance assessments.
Analysis of the core content of the standard
ISO 9296:2017 provides a standardized framework for noise declarations for information technology and communication equipment (ITT equipment), mainly including:
- Declaration value determination method: calculation of the average A-weighted sound power level (LWA,m) and sound pressure level (LpA,m) of batch equipment
- Verification procedure: sampling inspection plan based on the statistical upper limit sound power level (LWA,c)
- Presentation specification: the declared value must include key information such as the statistical verification value Kv
Comparison of key technical requirements
| Parameters | Measurement standard | Unit | Permissible Error |
|---|---|---|---|
| Sound Power Level LWA | ISO 7779 | Bel(B) | ±0.1B |
| Sound Pressure Level LpA | ISO 11201 | dB(dB) | ±1dB |
| Verification Value Kv | ISO 7574-4 | Bel(B) | N/A |
Key points for implementation
Declared value calculation process
- Randomly select samples from the batch (≥5 units recommended)
- Measure LWA and LpA of each device according to ISO 7779
- Calculate the arithmetic mean and convert to Bel units (1B=10dB)
- Determine the verification added value using the formula Kv=1/10[1.514st-0.564σM]
Note: When the sample size is ≤5, the guard band correction factor in Appendix A must be used.
Background of Standard Evolution
Main changes compared to the 1988 version:
- New Normative Appendix A (Kv Calculation Procedure)
- Updated referenced standards to the latest versions, including ISO 7779:2010
- Clarified that the next version will use decibel (dB) instead of bel (B) as the unit of sound power level