dB(A) vs Frequency plot through NI9234

[FightOnSCTrojan]

I am trying to make a plot of dB(A) vs. Frequency of an auditory signal. The DAQ picked for this application is NI9234. Using the help of this forum, I managed to get a display going of dB(A) over time. So far so good.

Where it gets murky (sorry for my lack of background in signal processing) is when I try to get into the frequency domain.

1. Do I wire the original signal (SPL vs. time) or converted dB(A) versus time into FFT/ Spectral analysis?
2. Once I apply FFT, it is my understanding that my X is frequency. What is my Y? is it dBm? How to I convert my graph so instead of displaying dBm it will display dBA?

I am acquiring at max rate, (51.2K). I understand that by FFT, I will reduce my frequency spectrum by half (quite ok). All I need is to be able to understand my Y axis better. And if possible, convert that to dBA scale.

Thanks,

[Paul-D]

Hi there, this is Paul with Applications Engineering at NI.

There are many ways to accomplish the bode plots that you are looking to achieve.

The first solution we offer is our Control and Simulation Module for Windows (included in LabVIEW Professional), which will offer you an out of the box solution for the types of measurements you are trying to do.

It is also possible to do it yourself in LabVIEW, since a bode plot is just performing some math and plotting a signal.  I am not an expert on doing this work in LabVIEW, but here are some ideas and pointers.

I would check this thread from 2 days ago out:  https://forums.ni.com/t5/Signal-Generators/how-to-make-bode-plots-in-Labview-7-1-without-using-Contr...

Additionally, I think you need a better understanding of what these functions are doing, so you may need to pull some wiki articles on the ideas behind bode plots.

You can use our Context Help, and the Detailed Help within that to get a deeper understanding for what each function is doing.  For example, the following information is available in our help files uilt into LabVIEW:  https://www.ni.com/docs/en-US/bundle/labview-api-ref/page/menus/categories/signal-processing/anspect...

Try working some of those resources and see if you can make any progress.

Regards,