Final answer:
The statement provided in the question is false; xylophones use resonators made of wood or metal to amplify the sound, not metal tubes as suggested. Resonators enhance sound differently than the tubes in wind instruments.
Step-by-step explanation:
The statement that xylophones generally have metal tubes underneath that amplify the sound is false. The components that are often found under the bars of a xylophone are called resonators, which are typically made of wood or metal.
Resonators are designed to enhance the sound produced by the vibration of the bars when they are struck. The resonators act in a similar way to the tubes described in some wind instruments, which modify and amplify sound through changing the length of the resonating air column. However, in the context of xylophones, they do not function through changes in air column length, unlike the mentioned wind instruments such as tubas and piccolos.