ISO 3741 — Determination of sound power levels — Precision methods for reverberation test rooms
Sound power in the reverberation room, suited to broadband sources and products that are awkward in a free field.
At a glance
- Standard
- ISO 3741
- Published by
- International Organization for Standardization
- Title
- Determination of sound power levels — Precision methods for reverberation test rooms
- Status at ALT
- Traceable — outside the accredited scope
Accreditation status
This standard sits outside ALT’s accredited scope. The measurement is made to the method with traceable reference equipment, and the report says so plainly — it does not carry the accreditation mark. If your specification, regulator or customer requires an accredited result, tell us before you book and we will say whether we can meet it.
Before you commit to this standard
Two things decide whether a result to this standard will be accepted: whether the measurement was made by a laboratory whose scope covers it, and whether the specimen and conditions matched what the standard actually requires. A number produced outside either of those is not wrong, but it is not evidence either.
If you are not certain which standard your specification calls for — and specifications frequently name a superseded edition, or name an ISO standard where the ASTM equivalent is what the market expects — send us the clause and we will tell you what it means in practice before you spend anything.
Standards usually specified alongside it
| Standard | What ALT does with it | Status |
|---|---|---|
| ISO 3744 Determination of sound power levels using sound pressure — Engineering methods for an essentially free field over a reflecting plane | The workhorse method for machinery noise declarations, including EU Directive 2000/14/EC and the Machinery Regulation (EU) 2023/1230. | Traceable — not in accredited scope |
| ISO 3745 Determination of sound power levels — Precision methods for anechoic and hemi-anechoic rooms | Precision grade 1 sound power in the anechoic chamber, for products where the declared figure has to withstand challenge. | Traceable — not in accredited scope |
| IEC 60704 series Household and similar electrical appliances — Test code for the determination of airborne acoustical noise | Appliance noise declarations. The figure that appears on EU energy labels for air conditioners, washing machines, dishwashers and refrigerators. | Traceable — not in accredited scope |
| ASTM E477 Laboratory testing of ducted air distribution systems and air terminals for aerodynamic and acoustical performance | Insertion loss and regenerated noise of silencers and air terminals. | R&D measurement — not accredited |
| ISO 9614-2 Determination of sound power levels using sound intensity — Measurement by scanning | Sound power measured with an intensity probe scanned over a surface enclosing the source. The advantage over pressure-based methods is that it tolerates background noise and reflections, so a machine can be measured where it stands rather than moved into a chamber. It also localises where on a machine the sound power is actually coming from, which a single pressure-based figure cannot do. Traceable, outside our accredited scope. | Traceable — not in accredited scope |
| ISO 9614-3 Determination of sound power levels using sound intensity — Precision method for measurement by scanning | The precision-grade version of the scanning intensity method, with tighter requirements on scan control and on the field indicators that qualify the measurement. Used where the result has to be defensible rather than indicative — declared noise emission, competitive comparison, or a figure that will be challenged. Traceable, outside our accredited scope. | Traceable — not in accredited scope |