I am very new to audio processing and I am using matlab to produce a signal to be presented through an audiometer.
The way I am doing it is as follows:
1) Set the dB amplitude level in my GUI to 0dB (I have been told to use 0dB as the max and anything below to reduce the levels and not go above 0dB)
2) Use the audiometer to calibrate it such that the dB I read on the dB meter is 80dB
Now if I want to reduce the dB level by 6dB so now the input is -6dB, the reading on the meter is more like 78dB ish and not 74dB as I expected.
Why is that so?
The code I am using is as follows:
Fs = 16000;
t = 0: 1/Fs : handles.duration*(Fs-1)/Fs;
fa1 = 10^(handles.level1/20);%calculating the factor to multiply the signal by
y1 = fa1*sin(2*pi*handles.freq1*t + handles.rad1*pi)';% actual signal