Some of the solo arias pose bold challenges for singers: the only solo tenor aria, "Olim lacus colueram", is often sung almost completely in falsetto to demonstrate the suffering of the character (in this case, a roasting swan). The baritone arias often demand high notes not commonly found in baritone repertoire, and parts of the baritone aria "Dies nox et omnia" are often sung in falsetto, a unique example in baritone repertoire. Also noted is the solo soprano aria, "Dulcissime" which demands extremely high notes. Orff intended this aria for a lyric soprano, not a coloratura, so that the musical tensions would be more obvious.