Even audio levels takes work.
There is a free Audio Editor that is very good with adjusting the levels farily easy.
The Name is Audacity.
http://audacity.sourceforge.net/
Get Lame and FFMpeg libraries to export MP3 and MP4.
The current Version is 1.3.12 (Beta) it is pretty stable.
The method I use in Audacity, is load the audio clip into audacity, Ctrl+A (Select all), on the Effect Menu > Normalize (to remove any D.C. offset). Then Effect > Amplify (I set the New Peak Amplitude to -1.0 to avoid clipping). The amplification level is automatic.
Export the file in the format of your choice.
Repeat for each audio clip in your video.
Otherwise in PD8 you go into the Audio Mixing Room and adjust the level of each clip. And Yes, it is a guess or by ear.
Carl312: Windows 10 64-bit 8 GB RAM,AMD Phenom II X4 965 3.4 GHz,ATI Radeon HD 5770 1GB,240GB SSD,two 1TB HDs.