Can't obtain running Leq from recorded data

[NickSeif]

I have recorded some data using SignalExpress and Nose and Vibration Toolkit, 2010. I'm using a Larsen Davis mic with an NI9234 and NI9162.

Basically, i have set up a few displays to monitor the data being recorded in realtime. One of these is running Leq. The values during recording look reasonable. I specify that i want to save the sound pressure, and the running Leq, then record some test data.

I then move to playback, and create a Sound Level step and add a running Leq display to Data View. The displayed data does not match what was displayed during recording. If i add a running Leq display to Data View direct from the data set, it works fine. (see the image below).

What am i doing wrong? i assume that it is possible to produce running Leq once data has been recorded...?

[NickSeif]

Also, I should have mentioned that it doesn't mater if i use the filtered sound pressure, or the unfiltered sound pressure as the input for the Sound Level step, both have results which are negative (and don't match what was recorded).

[NIthan]

Hey Nick,

As I said in the email I sent you with regards to SR number 1775179, this is a known issue with SignalExpress. Basically what is happening is you are getting a different dB reference level for your playback vs your real time recording. The playback defaults to a reference of 1.00, so if your signal average is 0.005, then in dB it should show around -45dB (which it does). 

Workarounds 
#1. Export newly collected data for post-processing while in the Monitor/Record mode (can't be done if reprocessing old collected data that can only be viewed in the Playback mode). 
#2. Export old collected data for reprocessing while in Playback mode, then correct the dB reference on the exported data. 
The dB reference can be corrected by running a LabVIEW VI within the project. Use a 'Run LabVIEW 2010 VI' Step to call Sound and Vibration VI 'SVL Set dB Reference (N Ch - 1 Ref).vi' You will have to save the VI as reentrant before using it in the 'Run LabVIEW 2010 VI' Step. 

-Nathan H