6 Tips for a Successful Sound Measurement

Before beginning a measurement project, it is crucial to set up your sound level meter properly. This step will help save time and prevent the need for rework. Additionally, it is important to conduct your sound measurements in accordance with regulations. In this article, we will discuss six tips for achieving accurate sound measurements.

1) Time: Syncronise Time on your Sound Level Meters

During most measurements, you will be taking notes on events that are relevant to the report, often noting event times from your watch or phone. It’s important that the time on your sound level meter matches your timepiece, so that your notes match the recordings on the sound level meter. This becomes even more important when using two or more sound level meters.

2) Logging and Reporting: Setup Measurement Interval

Some standards and regulations dictate specific measurement intervals. If your sound level meter supports logging at multiple time intervals, consider setting the report period according to the standard’s requirements, and a shorter time for the logging period. This way, you combine the convenience of directly measuring the values for your report with the ability to investigate and correct short disturbances. This can make life a lot easier when you start writing your report.

3) Data Storage: Check Storage Capacity for Measurements

This is a pretty basic point: Remember to check that you have enough free space on your memory card for the measurements you are about to make. Regularly deleting old measurements after they have been safely downloaded and stored is a good habit to keep, as is keeping a spare memory card packed with your sound level meter.

4) Sound Recording: Record Ambient Sound

Sound recordings can be invaluable when post-processing your measurements, for identifying noises or performing detailed analyses like FFT-based tonality assessments. If your sound level meter supports sound recording, make sure to set it up to measure at the right resolution and sample rate for your needs. It should be noted that audio recorded with automatic gain cannot be used for analysis afterwards.

5) Weighting and Bandwidth: Set up weighting and bandwidth for your measurement

It is best to make sure that you measure the right frequency weighting and bandwidth for frequency analysis. While it is common practice to post-weight spectra or to combine 1/3-octave bands into 1/1 octaves, there are potential pitfalls to both. Post-weighting can introduce significant errors when there are strong tones far from the centre frequencies. And while summing 1/3 octave bands works well for Leq data, it is not valid for many other parameters, like statistics or even Lmax or Lmin.

6) Extended Low Frequency: Be Careful with Measuring Low Frequencies and Wind

Measuring with an extended low-frequency range can increase the effect of wind-induced noise in your measurements, particularly those made with the Z frequency weighting. So, only include extended low frequency when very low frequency noise is relevant.