Somebody answered while I was standing there, and this is what I saw.
I need to be careful, because the obvious objection is that I have painted a sound as a light and that this is a cheat. It is not a cheat and it was not a decision. I had this panel drawn and blocked in for two weeks and the speaker was a dark circle of holes and the picture was dead. Then a voice came out of it at about seven in the evening, one word, and my eye did what eyes do, which is to go instantly to the source, and the source was a circle of small openings in brass with something coming out of them.
There is only one way to paint that and every painter for four centuries already knows it.
Light, in rays, radiating from a small aperture into a dark field. That is how the tradition renders a message arriving from somewhere the viewer cannot see. It appears in every annunciation ever made and it appears there because it is the correct solution to the problem, which is that a communication has no appearance and has to be given one.
So the grille is blazing. The rays come out through the perforation pattern and spread, and they are warm, and they are the only warm thing in the picture. Everything below is in shadow.
Below is the grid of name buttons, four columns, in near darkness, and I have kept them there deliberately. The names have nothing to do with this event. Whoever spoke did not identify themselves and did not need to. The whole apparatus of twenty-four labelled buttons is a system for specifying a person, and at the actual moment of contact it becomes irrelevant, because a voice came out of a wall and that is not a thing you can be confused about.
What was said, since somebody will ask, was one syllable, and it was not a word. It was the sound a person makes to indicate that they are present and listening and would like you to go first. I could not spell it if I tried.
I want to note the physical fact underneath all of this, because it is better than the metaphor. The reason the sound seems to come out of the holes in rays is that it genuinely does. The perforations are the aperture. The pressure wave leaves through them and spreads from that circle exactly the way light spreads from a small source, according to the same geometry, falling off with the same square of the distance. A speaker grille is an aperture for a wave.
I painted what the object does. That it looks like a four-hundred-year-old convention for the arrival of the holy is not my doing and I have decided not to be embarrassed about it.