Sound power is the energy of sound per unit of time from a sound source. The sound power level is a degree of the sound power in relation to a reference measure. Sound power is typically determined according one of the following methods:
- Measure the sound pressure due to the source in a free (or essentially free) sound field, and then determine its sound power from the sound pressure measurements. The free field solution is affected by standards – ISO 3744, 3745, and 3746.
- Using a technique similar to 1, measure the sound pressure due to the source in a diffuse sound field.
- Measuring sound power in a reverberation chamber is another common technique that is less expensive than traditional free field techniques – ISO 3741 and 3743.
- Taking direct measurements of sound intensity in any sound field to determine the sound power of the source. ISO 9614-1 and ISO 9614-2 are relevant here.
The pressure-based methods are most often used for production audits and high-volume testing (with specific standards for information technology equipment), while the intensity-based methods are generally used for engineering and in-situ measurements. For this method, sound power calculations can be performed directly on SignalCalc Dynamic Signal Analyzers.