Sound Power and Sound Pressure

The increasing requirements for indoor and outdoor noise levels set by international standards and legislation mean that today’s manufacturers must be able to provide precise specifications for their products’ noise levels. For determining the noise emissions of products, sound power is the preferred quantity to investigate because it measures the absolute power of a noise source independently from its acoustic environment.

Product noise levels have become increasingly more important to buyers of tools, appliances, machinery and other equipment. Purchasers seek to ensure lower noise exposure for both users and bystanders.

To encourage lower product noise, regulations such as the EU Directive 2010/30/EU require that products clearly display their sound power levels. This provides open information that facilitates the consumer’s choice and promotes competition on lower sound levels.

Undisputable Noise Levels

In order for noise labels on products to be effective, they must be based on fair and comparable measurements. Sound power represents the absolute acoustic energy of a product, independent of the acoustic environment. To keep test methods identical, standards stipulate the exact methods you must use to measure noise from any type of equipment, from household appliances to earth-moving machinery. Brüel & Kjær’s solutions are designed to support a wide range of relevant EU and international standards and to guide users through each one of them.

Sound Power Measurements

It is possible to calculate sound power based on several different types of measurements, depending on your test object. Sound intensity-based methods are used for in situ measurements and product engineering, making them ideal for fixed objects like extractor fans.

Reverberation room-based sound power and free-field-based sound power measurements are most often used for production audits and high-volume testing of products such as household appliances.

Brüel & Kjær is deeply involved in the creation and maintenance of measurement standards. Important standards include IEC 60704-2-4 for washing machines, and ISO 6393, ISO 6394, ISO 6395, and ISO 6396 for outdoor machinery.