Calculate decibels

Question

I\'m recording mic input using the XNA library (I don\'t think this is really technology specific, but it never hurts). Every time I get a sample I would like to calculate

Answer 1

I think Yann means that Decibels are a relative scale. If you're trying to measure the actual Sound Pressure Level or SPL, you would need to calibrate. What you're measuring is dBFS (decibels full-scale, I think). You're measuring how many decibels quieter the signal is than the loudest possible signal the system can represent (the "full-scale" signal, or 32768 for these 16-bit samples). That's why all the values are negative.