Measurement Instrumentation: The
sound level meter
The instrumentation used to measure ambient noise levels is
described in ANSI S3.1 – 1991. The
ambient noise level in the testing environment needs to be measured with a sound
level meter or an octave or one third octave band filter or equivalent filter or
frequency analysis system. Of these
instruments, the one most likely to be encountered by an Audiologist is a sound
level meter.
Below
is a picture of a Bruel and Kjaer sound level meter (model 2232).
The sound level meter that is used to make ambient noise measurement
needs to meet ANSI requirements.
In the clinical setting, an Audiologist is unlikely to interpret
manufacturer specification for devices such as sound level meters.
However, I am including this information for reference value in case the
occasion arises (i.e. when addressing specific questions about such a device to
a person calibration your equipment).
|
- sound
level meter used needs to meet the requirements for a Type I device
specified in ANSI S1.4 – 1983. A
Type I device simply means that the value measured by the sound level
meter is accurate to 1 dB.
- filter
must meet requirements for either an octave band or one-third octave band
filter or equivalent (specified in ANSI S1.11 – 1986).
- sound
level meter & filter combination (including microphone) will have
self-noise > 3 dB below
maximum permissible ambient noise SPL specified in table II for octave
band or table III for 1/3 octave band
- if
measured ambient noise SPL is between 10 and 3 dB greater than self-noise
of the sound level meter and filter combination, a correction value needs
to be applied
|
|
Note: This site is
best viewed using IE 4.X or higher under 800x600
resolution
|
