Which term describes lines moving in the same direction but not maintaining the same interval?

Which term describes lines moving in the same direction but not maintaining the same interval?

• A. Similar motion
• B. Parallel motion
• C. Oblique motion
• D. Appoggiatura

Answer: (A)

Two lines moving in the same direction but not keeping the same distance apart describes similar motion. Both voices rise or both fall, yet the interval between them changes from moment to moment. This is distinct from parallel motion, where the two voices move in the same direction and keep the same interval (often a perfect interval). Oblique motion is when one voice moves while the other stays still. Appoggiatura is a melodic ornament, not a relation of motion between two lines. So, similar motion best captures the idea of moving in the same direction while the interval between the voices changes.

Two lines moving in the same direction but not keeping the same distance apart describes similar motion. Both voices rise or both fall, yet the interval between them changes from moment to moment. This is distinct from parallel motion, where the two voices move in the same direction and keep the same interval (often a perfect interval). Oblique motion is when one voice moves while the other stays still. Appoggiatura is a melodic ornament, not a relation of motion between two lines. So, similar motion best captures the idea of moving in the same direction while the interval between the voices changes.