Beeping isn't somebody screaming at you for making an error. Beeping is to make you aware that you're likely drifting into their lane/space and haven't seen them. However, if you continue to do what you're doing after a beep, then anything following that is telling you to sort yourself out.
I had to slam my horn for a good 10 seconds at a middle aged lady last night. In the centre of town, 3 lanes, one for left and two for going right. I was in the right lane, she was in the middle. I just had a feeling she was going to cut me up when the light turned green, she veered RIGHT ACROSS my lane, horned at her, she didn't move, kept on it and resorted to also flashing my high beams. She then cut back into her own lane to completely avoid eye contact with me at the next set of lights. Utterly clueless as to what she'd just done. Had I not suspected she was clueless, she'd have gone right into the side of my car.