Final answer:
The statement is false; polyphonic texture involves multiple independent melodic lines, not just variations of a theme. Renaissance music introduced polyphony, and timbre distinguishes sounds from various instruments like the guitar, which is a chordophone.
Step-by-step explanation:
The statement that when musicians play versions of the main theme in a slightly different way from other instrumentalists, it is called polyphonic texture, is false. Polyphonic texture refers to the simultaneous combination of two or more tones or melodic lines, which are independent from one another. This is different from simply playing variations of the same theme. In the context of Renaissance music, the introduction of polyphony marked a significant difference from the Medieval period's mostly monophonic Gregorian chant. With polyphonic music, multiple independent melodic lines or voices intertwine, each with its own significance.
Instruments that would blend together across the vocal range were in demand due to polyphony. In an orchestra setting, the timbre of different instruments allows each to have its unique character. For example, when a violin plays middle C, its sound, or timbre, is distinguishable from a piano playing the same note.
A guitar would be classified as a chordophone because it produces sound through vibrating strings. Additionally, musical adjustments by wind instruments through finger holes or valves, changing frequencies of the notes played, is a common technique within orchestras and ensembles.