Melody.
Synonyms:
harmony, music, symphony, unison.
Harmony is simultaneous; melody is successive; harmony is the pleasing correspondence of two or more notes sounded at once, melody the pleasing succession of a number of notes continuously following one another. A melody may be wholly in one part; harmony must be of two or more parts. Accordant notes of different pitch sounded simultaneously produce harmony; unison is the simultaneous sounding of two or more notes of the same pitch. When the pitch is the same, there may be unison between sounds of very different volume and quality, as a voice and a bell may sound in unison. Tones sounded at the interval of an octave are also said to be in unison, altho this is not literally exact; this usage arises from the fact that bass and tenor voices in attempting to sound the same note as the soprano and alto will in fact sound a note an octave below. Music may denote the simplest melody or the most complex and perfect harmony. A symphony (apart from its technical orchestral sense) is any pleasing consonance of musical sounds, vocal or instrumental, as of many accordant voices or instruments.