Final answer:
Modulation is the term for the shift from one key to another within the same composition, creating a new central tone and contributing to the transition from modal to tonal characteristics in Western music.
Step-by-step explanation:
The shift from one key to another within the same composition that brings a new central tone is called modulation. This is a common musical technique used to vary the mood and color of a piece, and is essential in creating a sense of progression and development throughout a musical composition. While transposition involves moving an entire piece of music up or down in pitch, modulation is a transition within the composition that changes the key center.
The increased use of root motions of fifths that occurred towards the end of the Renaissance period contributed to the breakdown of modal characteristics and the development of tonality, which is the basis for most Western music theory. Understanding the concept of modulation can also assist in interpreting the notations and harmonic progressions of composers, like those found in the works of J. S. Bach.
Signpost language, such as the term 'transition,' helps listeners follow changes in a piece, such as the shift between key ideas or actual key changes, which is vital in enhancing the listening experience.