Why is StreamPlayer's volume lower than other engine/audio player software?

:information_source: Attention Topic was automatically imported from the old Question2Answer platform.
:bust_in_silhouette: Asked By madicecream
:warning: Old Version Published before Godot 3 was released.

When the StreamPlayer’s Volume Db is default value 0, the sound volume is lower than unity3d obviously.

And when I set Volume Db to 10, the sound volume is correct.

Is it intended?