I have been doing an experiment regarding sound. I use an audio generator to produce a certain frequency of sound at a certain loudness. A microphone connected to my computer will record the sound and I find out the dBs of the sound using a computer software called Audacity.
The problem is, when I change the frequency of the sound without changing the volume (there are 2 knobs on the audio generator, one for frequency and one for volume), the volume of the sound (measured in dBs in Audacity) somehow changes.
For example, 100Hz gives me -30dB. But 300Hz gives -50.0dB. Can anyone explain this and possibly solve the problem for me? (many online sources and all that I have been learning states that frequency does not affect amplitude)