You have to down sample by a lot (easily 10-100x). That would essentially remove a lot of the information in the signal. If you low pass filter you essentially remove all the peaks and the signal looks much "quieter" than it actually is.
Agreed. In the worst case, the audio is simply a high-frequency tone - which the LPF removes, leaving the plot showing silence.
ahhh didn't see that one. Perfectly makes sense ! Thx for explaining.