4 sensors HC-SR04 and Processing.

Hi guys,

this is my first post on the forum. I'm a musician and sonic artist and i'm dealing for the first time with a video installation, in particular with both Arduino and Processing. I'm totally new at programming that's why i would like to ask you some questions and help. I need to realize a sculpture with 4 ultrasonic sensors on it (front, rear, left and right). I need to use the values coming from Arduino into Processing in order to change the behavior of my graphics elements. It is important that i know which value is coming from which sensor because the graphics should change according to the space. I managed to connect 1 sensor and read the value in processing but i can't manage to connect 4 of them. When i try i can read just the values of the first one and from the other ones i received just 0. Is there anybody who can help me with this 4 sensors Arduino sketch?

Thanks a lot