Recent developments in sound power level measurement standards

The Acoustical Society of America ANSI accredited standards committee (S12) and the ISO committee TC43 SC1 (Noise) have developed a series of standards for measuring sound power levels of products. The engineering method to determine sound power levels in a free field over a reflecting plane is ANSI/ASA S12.54, which is the national adoption of ISO 3744. This is the standard “of choice” for a large majority of manufacturers of equipment—from consumer products to industrial machinery. In order to address issues found by using the standard over the years, some of which rarely occur, ANSI/ASA S12.54 (ISO 3744) has become larger and more complex. The ISO working group began a project to simplify ISO 3744 in order to make it simpler, easier to use, and more understandable. Instead of attempting to cover 99% of the situations that could arise during testing, the main body of the revised standard will address 90% of the cases. The issues that occur infrequently will be moved into annexes, and some parts will be consolidated into other standards. The current status of these changes to ISO 3744 and plans for the other sound power level standards will be discussed.