Final answer:
The notion that the theme must always be easily heard in a theme and variations form is false. Variations can significantly alter or obscure the original theme, and a composer has artistic freedom in how they present the theme and variations.
Step-by-step explanation:
The statement that the only basic rule of theme and variations form is that the theme must always be easily heard is false. While it is important that the theme remain recognizable throughout the variations in a piece of music, it does not always need to be easily heard. Variations can be quite complex and far removed from the original theme, to the point where the theme is not immediately obvious to the listener. This is particularly true in modern or contemporary variations, where the composer might introduce significant changes in rhythm, harmony, tonality, or even a deconstruction of the theme itself, which may obscure the original melody or motif. The essential idea is that the composer uses the original theme as a starting point to explore new musical territory, but there is considerable artistic freedom as to how this is done. The specific characteristics of a musical instrument, such as overtones and fundamental frequencies, contribute to its unique sound, which can affect the perception of the theme.