46 Bedrock SMxx operating manual © Bedrock Audio BV, 2019
• On the bottom left of the screen you will find an “accept individual” but-
ton, which is not usually present in other measurement modules. Use this
to commit a measurement to memory, if you are satisfied (upon inspection
of the decay curves) that the measurement is valid.
• Once your first (valid) measurement is finished, press “accept individual”
• The letters and the numeral “#1” are now greyed out on the accept button.
• Now repeat the test procedure as many times as required, pressing “accept”
after each measurement. The serial number is incremented after each indi-
vidual measurement.
• Data from up to 20 individual measurements can be kept in the device
memory at the same time.
• In the “RT60 measurement details” screen, you can inspect the latest indi-
vidual measurement as well as the mean across all measurements.
• Once you are satisfied with the overall (mean) results, press the “Save” but-
ton (to the right of the “arm” button). Mean data from all measurements
are now permanently saved and the temporary memory is reset.
The capability of averaging measurement data adds complexity to the user interface, but
averaging is sometimes essential to arrive at valid end results. Note that averaging takes
place on the level of the individualy measured data points along the decay curve (so not just
across individually measured reverberation times).
In the table on the measurement details screen, a column is shown that indicates the status
(reliability) of the current average measurement for the corresponding frequency:
• A green checkmark indicates a healthy, reliable measurement. The
RT60 measurement data may be presumed accurate with a margin of error
of at most 0.1 seconds.
• A yellow exclamation point indicates that the measurement accuracy
cannot be guaranteed. This may have various causes. For example, the
signal-to-noise ratio may be insufficient (not enough dynamic range be-
tween the steady-state noise signal and the noise floor with the noise source
switched off). This may also happen if the signal fluctuates more than ex-
pected for a given frequency band and the resulting linear decay fit is poor.
• A red cross indicates that the result is statistically deemed unreliable. In
order to obtain a reliable result in the corresponding frequency band, av-
eraging across more individual measurements (adding to the overall meas-
urement time) is needed. If the red cross persists upon averaging across
multiple measurements, disregard the corresponding frequency band or
repeat the entire measurement series.
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