Hi,
Regarding the conditions for starting and stopping the record, when you say the sound is over and under the 'level', what exactaly do you mean?
As sound is a continuously varying waveform, the 'level' of the signal will vary really rapidly from positive to negative and through the 0 point in the time domain (several thousand times s second), so taking a level against each sample as a double won't really work.
If you're looking to check against the VOLUME of the sound wave, you should consider using a function to measure the power spectrum of the signal, which will give you an idea of the signal's relative volume - once you work out what the volume you get during a 'normal' acquisition is, you can then set some limits for LabVIEW to monitor.
If you need to check the level of a particular frequency (such as the bass or the treble), you'll need to do some spectral analysis and/or filtration to weed out the frequency of interest.
The functions available to do this in LabVIEW can normally be found under the Signal Processing - Spectral Analysis sub palette, or under the Express - Signal Analysis palette. You can find examples relating to using the Express signal measurement vis by looking at the context help, or browsing to:
labview\examples\express\Basic Spectral Measurement.vi
I hope this helps with your application!
Best wishes,
Mark
