Final answer:
Electric Counterpoint III, by Steve Reich, presents a trance-like quality through phasing and subtle changes, creating a hypnotic, minimalist piece, unlike traditional sonata-allegro or rondo forms.
Step-by-step explanation:
The expression of Electric Counterpoint III can be described as a trance-like effect with subtle changes. Steve Reich's composition for electric guitar and tape creates a mesmerizing soundscape through the method of phasing, where the same phrase is played on several instruments in steady but very slightly different tempos. This creates intricate patterns of sound that can indeed lead to a trance-like listening experience.
In Electric Counterpoint III, this effect is achieved by a process that involves a pre-recorded tape of several guitar parts with live performance layered over it.
This repetitive and evolving texture falls into the category of minimalism, where changes happen gradually, and the listener may perceive the composition as hypnotically repetitious with nuanced shifts in rhythm and harmony rather than a development of varied themes as in sonata-allegro or the clear returning sections characteristic of rondo form.