A DEP B757 FLT CREW EXPERIENCES A PROB WITH THEIR AUTOTHROTTLE SYS AND MAY HAVE VIOLATED THE SOUND ABATEMENT PROC WHEN DEPARTING RWY 19R AT SNA; CA.

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ALTHOUGH I HAD WE HEARD ABOUT DIFFICULT DEPS OUT OF SNA; I THOUGHT WE WERE WELL PREPARED FOR THE TASK AT HAND. THIS WAS MY SECOND TIME IN SNA AND FIRST EVER TKOF FROM THERE. THE LAST TIME I WAS THERE; I DEADHEADED BACK SO I MISSED MY OPPORTUNITY TO EXPERIENCE RWY 19 DEP OUT OF SNA. AFTER THE THOROUGH BRIEFING; I APPLIED MAX TKOF PWR. INITIAL ENG SCAN LOOKED NORMAL AND PWR WAS SET EXACTLY AT TARGET EPR. I HAD NO REASON TO SUSPECT AUTOTHROTTLE MAY NOT ENGAGE ON CLBOUT. DUE TO LACK OF PRESSURIZATION; RESULTING IN LOUDER THAN NORMAL COCKPIT ENVIRONMENT; I DID NOT HEAR CAPT MENTIONING 'NO THROTTLE HOLD.' I THOUGHT I HEARD NORMAL 80 KT CALLOUT. AT THIS POINT; I WAS CONCENTRATING ON FLYING DEP AND MAINTAINING VREF +15 KTS. BY THE TIME I REALIZED THE ANTICIPATED BIG PWR REDUCTION DID NOT HAPPEN; WE WERE HEADING 175 DEGS AND ALREADY PASSED 1 DME MARK; STILL AT FULL THROTTLE. CAPT IMMEDIATELY PULLED THROTTLE BACK AND RECYCLED AUTOTHROTTLE SWITCH; AT WHICH TIME CLB 2 PWR WAS RESTORED. I FEEL THAT WE MAY HAVE TRIGGERED NOISE SENSOR NEAR 1 DME MARK SINCE PWR REDUCTION DID NOT HAPPEN AT THAT POINT. WE BOTH FELT REALLY BAD ABOUT WHAT HAPPENED; SINCE OUR COMPANY MAY BE FACING FINE OR OTHER FORMS OF PENALTY. I AM A RELATIVELY NEW FO ON THE B757 AND THIS WAS A HUMBLING EXPERIENCE FOR ME TO SAY THE LEAST. THE WHOLE THING HAPPENED VERY FAST AND CLRLY I WAS NOT AHEAD OF THE ACFT AS I SHOULD HAVE BEEN. ALTHOUGH OUR GND TRACK AND ALT WAS RIGHT ON TARGET; I SHOULDN'T HAVE TRUSTED AUTOTHROTTLE COMPLETELY TO BRING THE THROTTLE BACK. I DID LEARN A GOOD LESSON AND I WILL BE BETTER PREPARED FOR THAT DEP; AUTOTHROTTLE OR NOT. SUPPLEMENTAL INFO FROM ACN 585438: AT 80 KTS; 'THROTTLE HOLD' DID NOT DISPLAY; WHICH I ANNOUNCED AS 'NO THROTTLE HOLD' AT 854 FT; CLB PWR WAS CALLED FOR. SHORTLY THEREAFTER; I WAS BEGINNING TO RESTORE THE BLEEDS DURING WHICH TIME THE 1 DME FIX CAME UP FOR THE TURN TO 175 DEGS. AT THAT POINT; I NOTICED THAT THE COPLT HAD NOT REDUCED HIS PWR YET AND I PULLED IT BACK. BECAUSE OF THE DELAY IN PWR REDUCTION; I FEEL THAT WE MAY HAVE TRIGGERED A NOISE VIOLATION. I BELIEVE THAT THE INBOUND LEG IS MUCH EASIER TO STAY AHEAD OF THAN THE TKOF AND DEP SEGMENTS. FOR CREW MEMBERS NEW TO SNA; THE MORE EXPERIENCED PLT SHOULD FLY THE DEP. I HATE TO TAKE LNDGS OR TKOFS LIKE THIS AWAY FROM FO'S; BUT TO PRESERVE OUR OP; MAYBE IT SHOULD BE CONSIDERED A NECESSITY UNTIL GREATER EXPERIENCED IS OBTAINED THROUGH OBSERVATION.