Question

I’m currentyl building something like a tiny software audio synthesizer on Window 7 in c++. The core engine is running and upon receiving midi events it plays notes, changes programmes, etc. What puzzles me at the moment is where to put the 0 db reference sound pressure level of the output channels.

Let’s say the synthesizer produces a sinewave with 440 Hz with an amplitude of |0.5f| . In order to calculate the sound level in db I need to set the reference level (0 db). Does anyone know something like a default for this?

Answer 1

When decibel relative to full scale is in question, AKA dBFS, zero dB is assigned to the maximum possible digital level. A quote from Wiki:

0 dBFS is assigned to the maximum possible digital level.[1] for
example, a signal that reaches 50% of the maximum level at any point
would peak at -6 dBFS i.e. 6 dB below full scale. All peak
measurements will be negative numbers, unless they reach the maximum
digital value.