An interval of zero; i.e., the same pitch. Two instruments playing in unison are playing exactly the same notes.the playing of a melody by various instruments or voices, at the same pitch or in different octaves.<br><br>This term is applied to the group of two or three strings of equal pitch which comprise a single piano note.<br><br>Two pitches that are the same. Several singers singing a melody together<br><br>Several performers, instruments or sound sources that are sounding at the same time and with the same pitch.