Designed and built according to ISO 6926 and ANSI S12.5*.
For routine use in the following Comparison Sound Power Determination Methods:
ANSI S12.54, S12.10, ISO 3744, 7779, ECMA 74
The RSS 700 was designed to meet the needs of computer equipment manufacturers to determine the sound power of products that are relatively quiet at 25-70 dBA re one picowatt, and that must be measured at a radius of 1/2 meter (20″). This RSS 700 is less than o.25m in size, meeting the requirements of all the ISO series, viz. ISO 3746, for Reference Sound Source size. It emits a sound power of 65 dBA re one picowatt. A windscreen is provided to avoid windage effects on nearby microphones. It operated on 115vac, 60 Hz. It may operate at 50 Hz with a lower sound power emission (about 60 dBA re one picowatt.
The device called a “reference sound source” is used throughout industry and engineering where it is necessary to determine the amount of noise (sound power) that is emitted by a device (fan, vacuum cleaner, engine, etc.) into the surrounding environment. Though it is possible to do so by extensive sound level measurements in a controlled (lab) environment, such a process is tedious and uncertain without extensive calibrated acoustical equipment and certified procedures.
On the other hand, the much simpler “substitution (comparison) method” is possible, where the device under test (DUT) is operated in its natural environment while conventional sound pressure level (SPL) measurements are made around the DUT. The DUT is then shut off. The “Reference Sound Source” (RSS) is placed next to the inoperative DUT, switched on, and the SPL is again measured in the same way as before. The RSS sound power output has previously been calibrated by precise methods, so the sound power of the device under test is simply calculated as
DUT.PWL = DUT.SPL – RSS.SPL + RSS.CAL , dB re one Picowatt.
[One Picowatt = 10^(-12) watts.] With standard performance data (not individually calibrated):
*under the special condition that sound measurement is made on a o.5m radius surface