Why did the Titanic creak and groan, during the sinking?

Question

In the film I noticed the creaking and groaning got louder, as it sank more.. why was this? and where was the groaning more noticed within the ship?

Answer 1

It was a film...they were sound effects put there to heighten tension.

Answer 2

it is believed that the ship broke into two separate pieces as it was sinking below the water. The sounds heard were those of the steel bending and stretching and breaking.  

Answer 3

enclosed area - sound is louder

metal stressed in an unnatural fashion, i.e.- the ship did not want to sink - and as one part tried to float - the other was bringing it down