ACR ACFT RUNS OVER TOW BAR AT PSP; CA.

Narrative

WHILE PUSHING THE ACFT BACK AT THE PALM SPRINGS ARPT PERMISSION FOR ENG START WAS GIVEN BY THE GND CREW AND BOTH ENGS WERE STARTED. PUSHBACK WAS NORMAL AND THE ACFT WAS STOPPED AND STILL CONNECTED TO THE PUSHBACK TUG. GND PERSONNEL XMITTED SOMETHING OVER THE FLT INTERPHONE; HOWEVER BECAUSE OF A DEAFENING ENG NOISE FROM THE GND HANDLER'S HEADSET I LOOKED DOWN TO MY COM PANEL TO ADJUST THE FLT INTERPHONE VOLUME. LOOKING BACK OUTSIDE THE GND MARSHALLER WAS FRANTICALLY GIVING ME THE HAND SIGNAL TO SET BRAKES. I SET THE ACFT BRAKES AND MADE CONTACT WITH THE GND INTERCOM. HE INFORMED ME THAT THE ACFT NOSEWHEELS HAD PARTIALLY OVERRAN THE TOW BAR. THE ACFT COULD NOT BE MOVED; THE ENGS WERE SHUT DOWN AND THE COMPANY NOTIFIED. I THINK THE GND HANDLER'S FAILURE AT THE JETWAY TO SPEAK CLOSE INTO THE MIKE CAUSED ME TO SET MY COM PANEL INTERPHONE VOLUME TO A RELATIVELY HIGH POS. WITH THE ENGS RUNNING THE ENG NOISE THROUGH THE GND HANDLER'S MIKE; WHEN LATER OPENED; BECAME DEAFENING LOUD AND CAUSED THE SUBSEQUENT MISCOM AT A CRITICAL TIME.