Tone Analysis in noiseLAB Batch Processor 4.1

In the Danish comparative noise measurement in 2021, a bug was identified relating the 10% tone criteria. In the screen shot below the 51 Hz band should not have been identified as a tone.

The tone analysis was based on an FFT Spectrum with a line spacing of 3 Hz from 20 Hz to 10 kHz with linear RMS integration of 90 seconds and a linear (Z) frequency weighting.

Tone analysis in noiseLAB Batch Processor 4.1:

The current shipping version, noiseLAB Batch 4.1 can be used to check whether it shows the correct tone values with respect to the 10 dB criteria of the Critical Bandwidth (CB). In the above screen shot, you can see the broad red range centered at 51 Hz (red identifying it as an audible tone) has at 12.2% width of the critical bandwidth, exceeding the 10% of the CB (see the lower right hand corner). Hence it should not have been identified as an audible tone.

The bug is relatively rare, and is primarily seen with broad, relatively flat “peaks” at lower frequencies. 

The correct tone analysis is shown in an early version of noiseLAB 4.2B1 below:

For participants in “Store Støjdag” in Denmark 2021, the calibration value used was 94.0 dB, vs. 93.8 dB in the above analyses.

noiseLAB Batch Processor 4.2 (Beta) with the above bug fix is planned for mid-decemberand the final version early 2023. The upgrade is available free of charge for all existing users of noiseLAB Pro.

The above is available in Danish here Tone analyse og noiseLAB.

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