What you want IINA to do:
I suggest that the voice icon may be adaptive. For example,

• volume [67, 100] -> speaker + 3 lines
• volume [34, 66] -> speaker + 2 lines
• volume [1, 33] -> speaker + 1 line
• volume 0 -> same icon as mute / speaker with no line

or just make volume 0 has a different icon than others.

What IINA does currently:
Voice icon remains the same between [0, 100].

Why you think this should be added:
In music mode, there are no clues to trace the voice volume at a glance. Especially when the volume is 0, users may be struggled to look for the problem of no sound and not realize that it is because of the volume is set to 0.

I opened this issue because I couldn't find why IINA is not playing the sound and even reboot my laptop twice...

Examples of other projects that have something similar:
OSX