Page 7
Chapter 3
Measuring Sound
Always calibrate your instrument prior to, and after taking measurements using
a known sound source such as the Castle GA607 sound level calibrator. The
type of microphone supplied with your instrument is
Free Field
and requires an
incidence angle of 0°, therefore whilst measuring always point your Sonus
Pocket Meter directly towards the noise source being measured.
Sound Level – General Advice
In some environments, high levels of noise can occur. The Castle Sonus Pocket
sound meter has therefore been designed for complete accuracy up to sound
levels of 140dB.
Before you record measurements take the time to ensure you have chosen the
optimum range for the process to be recorded. Wherever possible, the
optimum range is when the average measured signal is approximately half way
between the top of the range and the bottom of the range without an overload
condition.
Where high levels of noise are encountered the meter may register an overload
and in these circumstances the meter will display that this has occurred, it is
therefore advisable to determine if an Over Load occurs on the selected range.
In such cases you will need to select a higher range to accommodate the higher
peak levels. See
Technical Specifications
for peak range limits on each
individual range.
If the noise levels are too low for the range selected then the meter will display
an under range condition. Under these circumstances you will need to select a
lower range.
For more detailed information see
Overload and Under Range Conditions
and
Measuring Ranges
.
If measuring low level noise then be aware of the inherent noise levels caused by
a combination of thermal and electrical noise from both the microphone and the
sound level meter. Measuring data that lies within 10dB of the lowest quoted
level on the lowest measuring range may be influenced by the self noise of the
system. See
Technical Specifications
for inherent noise levels and range limits.
