fiction - Background speech with foreground dialogue

A few days ago, I stumbled upon an issue of the type; meaning I had two characters talking between themselves and another character talking in the background; actually delivering a speech.

What the problem is, is that what the speaker's saying is important (for the most part at least) to one of the characters talking (could be both, but it was only one in my case).

I'm not sure how to get this in writing, as opposed to how easily this is done in movies (background speaker's volume is lowered by about half maybe while the characters in the foreground can whisper loud enough for the people watching the movie).

Should I maybe use some fancy formatting to set it apart from the foreground dialogue?

Such as:

"The individuals or groups responsible for the senseless bombing..."

She approached him taking care not to make any noise or disturb anyone around her. She seated at Jimmy's right side and peered at him. "What's going on?"

"... will bear the full weight of justice."

He grimaced from the interruption. "The President's delivering his statement about the bombing yesterday."

or with more interaction between the characters:

"Is any of you strong enough to hold the rubble while we get inside? I wouldn't want to..."

Tommy was about to step forward to help, but was interrupted by Sydney. The latter visibly was out of breath. "Finally I found you! Bad news, other regions have been affected and the damages have been far reaching."

"Yes, like this, but this isn't enough, I'll need more..."

Tommy bit his tongue. He couldn't leave everyone here, no matter how hard he wished to. "What is the progress towards clearing the exit?"

"Hey you there! Could you leave your damsel and give me a hand?"

Or is there a better/more effective way so that readers don't get confused? The speech styles of all the characters involved may not necessarily be different. Or is this something to be avoided in writing completely?

EDIT: The speaker in my case will soon interact with the other characters as well. It seems relevant, so I added another example.

Answer

I think your first example is perfect, making sure that you drop out words from the speaker to indicate the passage of time as your foreground characters are talking "over" the speaker. It makes perfect sense to me as a reader what's occurring.