Sirens

What´s the deal with the sirens on top of police cars?
The light makes sense, cause the people in the street see it and can react like making space for the police cars.
But do they need the sound? I mean, people in their cars might not even hear it! When someone is listening to loud music he would just hear it as the background of the song and think that it´s a bad remix version of his favourite song!
And what are the burglars supposed to think?
“Oh, the police is coming close, let´s wait for them and have a nice shoot out!”
That doesn´t make sense at all!
So my recommendation for the police is:
“Keep it down and you might be more successful in the war against crime!”
And what´s the deal with sirens of ambulances?
I don’t want to get disturbed in the middle of the night cause someone who I don´t even know is dying!
Everytime I get disturbed during my sleep I hope the one already is dead when the ambulance arrives at his place..so the ambulance car at least doesn´t need the siren on the way back!

I wish I had a siren when I´m about to come, so I wouldn´t have to shout it!