What you took to be wheels down noise was far more likely to be engine power up after reducing speed to final approach speed.
Sound heard was an extended moter whirring, doors opening sound of the doors in slip stream (rushing wind) then a loud thunk including the floor shuddering enough to cause my IFE screen to tilt and then moters again and the sound of doors closing with the sound of the slipstream subsiding.
While not even close to your flying experience, I did here the sound of the engines a short while later...... they were more uniform and had the familiar spooling up sound.