What are those weird noises we hear during flight?

I found this information interesting... and reassuring! And I'm looking forward to explaining away the roars and thumps to my ever curious 4 year old next time we fly. It's taken from the Boeing website.

In the early days of aviation it was common for people to refer to airplanes as "flying machines" -- and that's exactly what they are. When you're flying, you're inside a large, complex machine, so it's common to hear a lot of strange sounds. Here are some of them:
A drilling sound prior to takeoff and on approach to landing That's the sound of the flaps and slats being extended on the wings. These panels, which increase the area and curvature of the wing when extended to facilitate low-speed flying, are driven by a screw mechanism that causes the noise you hear.
A high-pitched whine prior to take-off That's the sound of the engines spooling up for take-off. Once airborne, the pilot will throttle the engines back, and during cruise the sound of the engines becomes more of a hum than a whine.
Rattling during takeoff or turbulence That's the sounds of things being jostled in overhead bins and other parts of the cabin due to engine vibrations on takeoff or turbulence during flight. It's not the sound of the airplane breaking apart!
A thump beneath the floor following takeoff That's the landing gear going up into the belly of the plane and the doors to the landing gear bay being shut.
A loud roar following touchdown That's the sound of the thrust reversers, which help slow the plane once it's on the runway. They literally reverse the flow of the air through the engines which is why they are so loud. Airplanes are designed to stop using breaks alone, but flight crews typically deploy the thrust reversers to help save wear and tear on the braking system.