I've had this happen. You can try to change pad brands, that usually fixes it. The disc brake quiet goop you put on the back of the pads also can help in some cases.
But, you might want to leave it alone.
Where I live, people glare at you if you touch the horn - no driver uses their horns, it's considered bad form, I guess. I can live with that - except that at every street corner pedestrians constantly walk out into the street - in front of cars - against red lights - you name it.
I found when I approached a stop sign that if I lightly touched the brakes the things would squeal the loudest - so I would get them screaming a block or so away - and by the time I got to the sign the noise would have cut through to even the most stoned/high/moronic pedestrian and they would be backing away from the curb, not running out in front of me.
It was a sad day when those pads wore out - and I have never been able to get replacements to scream like that.