Variation in Back-to-Back Tests

[ali.tabibnejad]

I am getting variation in waterfalls in back to back tests. Is this to be expected? What am I doing wrong? My personal position is the same as well as everything else under my control. Yesterday, under fairly similar condition I got the most different and promising waterfall. I'm very new to all this. ANY help (in reading these, etc.) would be appreciated.

 

[Wayne A. Pflughaupt]

Waterfalls are only useful up to about 300 Hz.

Things like the A/C kicking on, or someone opening a door (i.e. an open floor plan, where it might escape notice) can cause pressure changes that would show up on a measurement.

From one day to the next, changes in temperature and humidity can make a difference, too. Transducers (both microphone elements and speakers) are affected by these things - not enough to hear, but enough to show up in a measurement

Regards,
Wayne

 

[John Mulcahy]

If you are referring to the parts below the blue band, that's background noise.