Vehicle Pass-By Noise

You can use the Peak mode of the Spectrum Averager to determine how much noise a vehicle makes as it passes by at a fixed distance. You just start the "average", wait for the vehicle to pass, and then hit Pause to see the result. You don't usually need to worry about precise timing because the vehicle will be much louder than anything else at most frequencies, so the peak will only reflect that one source.

Note that you can obtain a single dB value in addition to the spectrum. You can specify a selected portion of the spectrum with the solid and dotted cursors, and use the Sigma readout mode to get the included energy between them. You can use the Spectrum Curves dialog to apply a Weighting Curve, either a standard curve such as A or ITU-R 468, or a custom curve that you define.

Alternatively, you can use the Peak Hold option of the Sound Level Meter to get a reading of the overall spectrum, with or without the same Weighting Curves.

See also Automotive Applications