This tutorial is available from within Sonneta by selecting Help > Calibration Tutorial.
This tutorial walks you through the steps to calibrate Sonneta and understand how background noise affects your measurements. It assumes no prior knowledge of Sonneta. You will need a sound-level meter for this tutorial.
Before recording sound samples, you must select the sound input device. Select Sonneta > Preferences… from the Sonneta menu, and then click the Sounds tab.
- Select your input device from the list. You can click the question mark button at the lower-right of the Preferences window to get help.
- For the sake of testing, you can use your computer’s internal microphone. However, it is essential to use a higher-quality mic for collecting real data.
- Close the Preferences window when you are done.
- If you are using the computer's internal microphone, you will have to disable ambient noise reduction.
- From the Apple menu, select System Preferences… and click the Sound icon.
- Click the Input tab at the top.
- Uncheck the "Use ambient noise reduction" check box.
Sonneta’s online help provides more information about setting up your assessment environment.
Calibrating the dB-scale
- If there is an "Untitled" document open, you can close it.
- In order for Sonneta to measure sound pressure levels, you must calibrate your microphone. Select Analysis > Calibrate dB-Scale… to perform a calibration.
- Click the question mark button at the bottom left of the window and follow the detailed instructions on how to perform the calibration.
Sonneta will remember this calibration as long as you use the same audio interface (and plug it into the same port on your computer). If you change any device setting in Sound Preferences, you will need to recalibrate.
Calibrating for background noise
- In order for Sonneta to measure signal-to-noise ratio and recording quality, you must do a noise calibration. Select Analysis > Calibrate Noise… to perform a calibration.
- Position the microphone at the location where samples will be recorded in the assessment room.
- Watch the sound level indicator. If the bar is green, the background noise is within the recommended range for a good measurement. If the bar is yellow, the noise level is adequate for a measurement, however, conditions are not ideal. If the bar is red, the noise is too high to make a valid measurement.
- Select Sonneta > Preferences… from the Sonneta menu, and then click the Calibration item in the toolbar.
- Try checking and unchecking some of the measurement items in the Measures of Interest area. Note how the locations of the red and yellow limits change on the sound level indicator. To make valid shimmer and HNR measurements usually requires a very quiet room and a head-mounted microphone. This is true with all acoustic measurement tools, but only Sonneta shows you this graphically. Uncheck the shimmer and HNR measures if they are causing the sound level indicator to be in the red, and close the Preferences window.
- Click Record to make an 8 second measurement of the background noise. (Try to be silent while it records.)
- You now have a fully calibrated system. You can click the question mark buttons at the bottom of the Calibrate Background Noise and Calibration Preference windows to learn more about how noise affects your measurements.
- Sonneta’s online help provides more information about setting up your assessment environment.
Recording sound samples
The Essentials Tutorial discusses how to make measurements with Sonneta. However, after doing calibrations, you will notice some things are different. The sound level indicator in the Recording window will now be color-coded to show when the signal-to-noise ratio (SNR) is appropriate for your measures of interest.
Also, after recording the SPL (dB) column of the measurement table will show the average SPL for the sample; and the SNR column will show a 5-star rating for the recording quality. Control-click these table columns and select Help from the contextual menu to learn more about SPL and SNR.