The Dialog Normalization is a field in AC3 and DTS header (not used with other formats) than can force the decoders to attenuate the volume to obtain the same level between tracks...(in a ideal world).
Some decoders ca be forced to ignore the Dialog Normalization, but not others.
In AC3 header the field store a value between 0 and 31 (-31 dB), if is 27 (many times) the volume is attenuate 4 dB, if is 31 -> 0 dB (no attenuation).
Remove the Dialog Normalization is store 31 in this field to avoid attenuation. After that all decoders produce the same output (the source without attenuation).
In DTS header the field value is directly the value to attenuate, but is rarely used, between dozens of samples I only found one to force -4 dB, the rest are always 0.
I never see problems with DTS volume.
The problem is only when follow Dolby recomendations explained here:
How To Properly Encode Dolby Digital Audio (AC3) because we obtain low volume compared with CD-Audio, TV commercials or other audio encoded with other formats (MP3, AAC, FLAC, ...).
The free AC3 encoders by default put 31 in Dialog Normalization to be comparable with other sources.