What is a passing tone in music theory?

A passing tone, also known as a passing note, serves as a melodic connection between two consonant tones, typically functioning to create smooth stepwise motion within a melody. In the context of music theory, it provides a transition between notes, filling in the space between the established tones. This often enhances the melodic contour and adds a level of embellishment to a musical line.

In contrast, the other options describe different musical concepts. For instance, the second choice refers to a phenomenon where a note is approached by a leap and resolved by a step, which aligns more closely with the definition of a neighbor tone or an accented non-chord tone. The third option describes a sustained note, which relates to techniques like pedal tones or sustained tones rather than passing tones. Lastly, the fourth option speaks to a combination of consonant and dissonant sounds, which does not define a passing tone, since passing tones themselves resolve back to consonance and do not serve as a harmonic foundation. Therefore, the understanding of passing tones is critical as they enrich musical phrases by connecting pitches in a fluid manner.