How to Use SPL Compensation

How to Use SPL Compensation

The "SPL Compensation" tab in the SPL Config dialog allows you to calibrate an SPL meter to a location other than its monitoring location, so you can now "measure" SPL from a virtually calculated point in space where you might not actually be able to place a mic during an event, such as the middle of the dance floor or in the middle of an audience standing space. To do this, Smaart compares the levels of a test signal at both this audience listening point and the point in space where the mic will actually be located during the event, creating an offset for live SPL data.

1. Place your mic in its virtual listening position (or otherwise remote location that would be inaccessible to measured during a performance) and select your desired calibrated input using the drop down under "Step 1". This is the theoretical loudest location within the space that you are measuring. The desired result is a readout that would represent the SPL at this location.

2. Excite your system using pink noise and click "Capture" under "Step 2". This takes roughly 20 seconds. Generator controls are conveniently included here for this reason. You can turn the noise on/off as needed, but it is not done automatically. Pink noise is recommended at a suitable level above noise flor to represent the entire broadband energy that the system would be capable of reproducing during use.

3. Move your mic to its actual measurement location. Select your input again under "Step 3". This is the location which will have the offset applied, representing the location chosen in "Step 1". You can either select the same calibrated input or a different one (when the same microphone is selected, Smaart assumes you have moved it). This input will be mirrored as a new selectable "compensated" input.

4. Run pink noise through your system at the exact same level as before and click the second "Capture" button under "Step 4". When you press this button, 15 second LAeq and LCeq measurements are calculated and compared to the values previously calculated at the Loudest Location. The resulting offset for A and C weighting will appear in the text fields under "Step 4".

5. Click "Add" to save these offsets as a compensated input. By default these are named after the original input followed by "(compensated)", but you can rename them if desired. These inputs are display-only and won't create data in any generated logs.

6. When selecting an input for an SPL meter or to set an alarm, your compensated input(s) are now available for selection, although they won't generate data for a log.

Compensation is only applied to A- and C- weighted metrics, which will be the only metrics available in the metric drop down for a compensated input. If the LAeq and/or LCeq correction fields are set to 0, the metrics for that weighting are shown in red to indicate that a compensation offset has not been set.