To detect phase changes you have to turn them into amplitude changes. It then makes sense to call the phase-change-turned-amplitude-change a "phase change." Yes

To detect phase changes you have to turn them into amplitude changes. It then makes sense to call the phase-change-turned-amplitude-change a "phase change." Yes, this elides a critical part of the interpretation, but if we were to insist on carrying around a complete interpretation with every noun we'd wind up with nouns as long as textbooks. Even Germans don't take it that far.