Hi DaPuCZ,
What signal are you primarily interested in measuring? This will affect
the microphone type (free field, pressure field, random incidence),
microphone size (based on frequency response and dynamic range), and
preamplifier. For ease of use with the NI-9233, you will probably want
a prepolarized microphone to make use of the IEPE signal conditioning
from the NI-9233 and a preamplifier with a BNC output.
I would also recommend looking at some additional resources such as
this guide from G.R.A.S. Sound and Vibration and this guide provided by PCB Piezotronics. Here is a list of some additional vendors where can get your microphone. Let me know if this helps.
Regards,
Kent
Applications Engineer