Advanced composite is an energy absorbing material. Noise vibrations through the structure are absorbed which has a noise reducing effect.
Due to their rigidity and non-energy absorbing nature, aluminium - as other metals - are an effective transmitter of noise. In order to reduce internal noise to an acceptable level, acoustic noise-reducing insulation has to be added. To be affective, acoustic insulation needs to be dense and so will increase vessel weight.
In addition, under tropical conditions these acoustic materials can soak up moisture causing added weight and deterioration of the insulation as well as supporting corrosion to the aluminium.