[Gerard M]

The C-5M Super Galaxy climbs higher and faster than its legacy counterparts while carrying more cargo over longer distances. It also requires less tanker support and is projected to have a much higher mission availability rate due to increased reliability.
The C-5M is the product of a two-phase modernization effort. The first, the ongoing Avionics Modernization Program (AMP), provides a state-of-the-art glass cockpit with modern avionics and flight instruments that meet future Communication, Navigation, Surveillance and Air Traffic Management requirements. Lockheed Martin is under contract to perform AMP modifications on 111 C-5 aircraft.

The Reliability Enhancement and Re-Engining Program (RERP) is the second phase of the C-5 modernization effort. It includes 70 enhancements or replacements of major components and subsystems, including the installation of GE CF6-80C2 commercial engines. The new engine produces more than 50,000 lb. of thrust – a 22 percent increase and is Stage 4 noise compliant.

The program delivers value on top of capability, with modernization paying for itself through savings in operation and sustainment costs across the fleet.
http://www.lockheedmartin.com/products/c5/index.html

Does this mean that the C-5's very distinctive engine noise will have changed with the new engines?