Final answer:
If more than eight glasses were used for the special instrument, more notes and songs could be played, but the notes would still sound lower.
Step-by-step explanation:
The question asks what would happen if you used more than eight glasses to make the special instrument described. By following the instructions given, we can see that the different sounds produced by tapping the glasses are based on the amount of water they contain. The more water a glass has, the lower its sound will be. Therefore, if you used more than eight glasses, you would be able to play more notes and maybe even play more kinds of songs, but all of the notes you played would still sound lower.