Describe the key elements that differentiate a commercially successful pop melody from an ineffective one, focusing on aspects of contour, phrasing, and memorability.

A commercially successful pop melody distinguishes itself from an ineffective one primarily through its contour, phrasing, and memorability. The contour of a melody refers to the shape it creates as it moves up and down in pitch. Successful pop melodies often utilize a balanced contour, incorporating both stepwise motion (moving to adjacent notes) and leaps (moving to notes farther away). These leaps aren't random, but are generally small and followed by movement in the opposite direction, creating a sense of tension and release. For instance, consider the opening melody of "Rolling in the Deep" by Adele. It begins with a relatively stable note, then leaps up, followed by a stepwise descent, creating a sense of drama and resolution within the contour. An ineffective melody might be too static, remaining on the same notes, or be too erratic, with large unpredictable leaps that don't resolve.

Phrasing in a melody refers to how the notes are grouped together. Effective pop melodies often employ short, concise phrases that are easy to grasp and repeat. These phrases might be presented in a question-and-answer format, or they might be slightly varied each time they appear. They often mirror speech patterns, making them feel natural and singable. Take the chorus of "Shape of You" by Ed Sheeran. The phrases are short, repetitive, and fall within a comfortable vocal range, aiding the listener's engagement. On the other hand, an ineffective melody might have overly long phrases that are hard to follow, or they might be phrased in ways that feel unnatural or awkward to sing.

Memorability is arguably the most crucial factor in a pop melody's success. A memorable melody is one that sticks in the listener's mind, inviting them to sing along and replay the song. This memorability is achieved through a combination of contour and phrasing, as well as the use of rhythmic motifs, repeated intervals, and melodic hooks. A "hook" is a short, catchy melodic phrase that forms the focal point of the song. It's often a memorable fragment that appears frequently throughout the track, particularly in the chorus. "Happy" by Pharrell Williams uses a very simple but incredibly catchy hook repeated throughout the song, becoming its defining characteristic. An ineffective melody lacks those features, usually blending into the background, being too complicated or not having a hook that grabs the listener’s attention and allows easy recall. Memorability is also heavily tied to the context; how a melody interacts with the underlying rhythm and harmony and how it aligns with the lyrical content. A strong hook combined with well-crafted contour and phrasing is what makes a melody memorable and commercially appealing. In contrast, ineffective melodies often lack these crucial ingredients, causing them to be forgettable and failing to leave a lasting impression.