Yes, the frequency is roughly proportional to engine speed. It should sound only a bit more than high idle. You won't hear much of a load unless you put on a 15 amp or greater 3-phase load. Or load each 15 amp 120 volt duplex outlet to near its maximum.
The governor gets its speed data from a sensor mounted on the transfer case mounted PTO. It is a Hall Effect sensor so it is possible it is out of adjustment and not picking up all the teeth so it is under reporting the actual speed, causing the governor to pull the actuator too much.
The other possibility is the governor actuator is over-adjusted, making it too sensitive. Does the engine hunt or overspeed, then underspeed? If so, it could be actuator misadjustment.
Do you have the wiring diagram placard on the generator compartment door? Follow that to make sure all components are connected under the panel cover. There is a ramp generator which partially compensates for the torque converter slip without overshoot (exceeding 60 Hz on startup). If disconnected, you will have issues.