Does it indicate that the track actually has audio? Or is the audio broken? What does red indicate here?
Oh, a traffic light? So red means audio is stopped? Well, I would never associate traffic light colors with sound. They are lights, something visible, after all...
While the Breeze icon theme uses color to signal state, I don't think that this is a good idea in general. Red speakers simply have no meaning in the real world, unless you happen to have a really powerful amplifier and are driving your speakers into over-temperature. (Here speaks the engineer, oh well.)
|New muted audio icons.|
So, instead of an ambiguous color we now use the hue-neutral visual clue of striking out the speaker. And so we got Kdenlive a new muted audio icon, as you can see on the right.
As a small optimization, the new muted-audio icons don't show any sound waves as the normal audio icon does.
I've also played around with a hollow speaker icon design. But that design doesn't work out correctly: does a filled speaker signal state? Does a hollow one? But striking out the speaker has a much clearer visual message: no sound here!
On a final note: what sign language do prohibiting street signs use when it comes to sound? Yes, I know: computer user interfaces rarely use street sign language. Alas, looking beyond one's own nose may be interesting.
Several European countries use the famous red stroke design here:
|No Honks Allowed (from Wikipedia Commons: PD License)|
No rule with exception, this time Estonia and Ukraine: they rely on the red border. No strike.
|No honking (from Wikipedia Commons: PD License)|