Which formula to process fft audio file ?

[LarryJ]

Hello,

In the audio processing field, after applying fft on a sound signal, sometimes, engineers use 10*log10(abs(value)) and some others just sqrt(i**2 + j**2) to get the amplitude of frequencies.

Why one instead of the other ?

Thanks,

Larry

 

[reidintransit]

the first is the amplitude value in dB the second is the magnitude of the amplitude value.