Basic Documentation

Sound Measurement Instrumentation
Siemens Building Technologies, Inc. 103
Sound Measurement Instrumentation
Whenever the sound level becomes an issue, it must be measured and quantified before it
can be resolved. Handheld battery operated sound level meters are available. These typically
have a tube-shaped microphone that protrudes out of the top of the unit and a meter or
display of the sound level at the selected octave band. Meters vary as to features with the
more sophisticated ones offering a digital display of sound dB levels. Some models even
provide a display in graphical format showing each separate octave band’s dB value as
separate bars or integrated into a dB curve.
A sound level meter should offer separate dB readings (octave band filters) for each of the
eight8 octave bands (63, 125, 250, 500, 1,000, 2,000, 4,000, and 8,000 Hz). It is even more
desirable if the meter can also provide a 31 Hz octave band reading.
Sound Measurement Procedure
Holding the meter in one’s hand and walking around a room is OK for initial general
examination to determine if there is a specific noise problem. However, when making actual
measurements for recording data, and when making before and after type measurements,
the meter should be affixed to a tripod and fixed so the microphone is at the 5 foot (average
ear height) level. Follow the specific manufacturer’s instruction manual to position the meter
with respect to the primary source of the sound. This may require the microphone tube to
form a certain angle (such as, 45 degrees) with the direct line to the sound source.
Record the dB level at all octave bands when taking data. (Use the Sound Measurement
form provided in the Appendix of this document to record sound level data.).
Use masking tape of other suitable means to mark or record the exact location of the meter
and tripod if they must be removed from the room, so that measurements taken at another
time will be consistent with the original measurement conditions.