Ayman al-Muqaddam, head of a team of experts looking into one of Egypt's worst air disasters, said the cockpit voice recording would be analysed to identify the nature of the noise, which Western governments have indicated may have been a bomb.
Islamic State militants fighting security forces in Egypt's Sinai Peninsula have said they brought down the Airbus A321, which crashed 23 minutes after taking off from the resort of Sharm al-Sheikh one week ago, killing all 224 passengers.
Fears that the crash was caused by Islamist militants led several Western countries, Russia and Turkey to suspend flights to Sharm al-Sheikh, stranding tens of thousands of holidaymakers and dealing a heavy blow to Egypt's vital tourist industry.
Muqaddam said the auto-pilot was still engaged when the crash occurred and debris were scattered over a wide area of the Sinai desert extending for 13 km (8 miles), adding that this was "consistent with an in-flight break-up".
The black boxes recovered from the crash site showed that a "a noise was heard in the last second of the ... recording". The recording will be send to a specialist laboratory for analysis.
Scientists have used such methods to examine the signature of dying cockpit recordings in aircraft bombings. Comparing the frequencies may help determine whether the sound recorded on the Russian jet comes from a deliberate or accidental explosion.
Muqaddam said his team, including experts from Egypt, Russia, France, Germany and Ireland, was considering "all possible scenarios for the cause of the accident" but had not yet reached any conclusion. He said structural fatigue, a fuel explosion and even lithium batteries carried by passengers could be a cause.
Referring to media reports that Western intelligence sources believe that the plane may have been brought down by a bomb, Muqaddam said no evidence related to those claims had been provided to his team.