AN EMB145 EXPERIENCED A LOUD AIR NOISE AFTER TAKEOFF WHEN THE CAPTAIN'S DIRECT VISION WINDOW SEAL DEPARTED THE AIRCRAFT.

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I DID THE TKOF. AFTER PASSING THROUGH ACCELERATION HT; WE EXPERIENCED A LOUD AIR BLAST NOISE IN THE COCKPIT. FROM WHAT I MADE OUT; THE LOUD AIR BLAST NOISE WAS COMING FROM THE CAPT'S DIRECT VISION WINDOW. I PUSHED THE DIRECT VISION WINDOW HANDLE TO SEE IF IT WASN'T CLOSED PROPERLY. IT WAS CLOSED PROPERLY AND IT WAS CHKED 'CLOSED L' ON THE BEFORE TAXI CHKLIST. I WAS UNABLE TO HEAR THE ATC CTLR'S INSTRUCTION AND THE FO'S COM. I TURNED UP MY COM VOLUME FOR THE HEADSET TO HEAR SOME INSTRUCTION GIVEN BY ATC AND INSTRUCTION REPEATED BACK BY THE FO. I LOUDLY TOLD THE FO THAT WE NEED TO RETURN TO LAND AT ZZZ. THE LOUD AIR BLAST NOISE IN THE COCKPIT WAS UNSAFE TO CONTINUE THE FLT. I TOLD THE FO THAT WE ARE NOT DECLARING AN EMER AND THAT WE ARE JUST DOING A PRECAUTIONARY LNDG. THE LNDG WAS A SUCCESS WITH A TAXI BACK TO THE GATE. DISPATCH AND MAINT CTL WERE NOTIFIED AT THE GATE. AFTER LNDG AND TAXIING BACK TO THE GATE; I NOTICED PIECES OF THE CAPT'S DIRECT VISION WINDOW WAS HANGING OFF FROM THE WINDOW AND MAINT CTL CONFIRMED THAT THE SEAL CAME COMPLETELY OFF.