Often songs make frequent use of vocables and other untranslatable elements. The guitar melody is punctuated by a series of sudden band-harmonized vocables. Scat singing is vocal improvisation with wordless vocables, nonsense syllables or without words at all. The name derives from the monosyllabic vocables (non-lexical vocalizations), "tra-la-la". Lyrics can be about any number of subjects, and often include vocables (meaningless syllables). He also compared the bridge's melodic non-lexical vocables to those in "Istanbul". Vocables, or non-lexical syllables are used, as are cadential and closing formulas. The song comprises non-lexical vocables (abstract sounds rather than semantic words). Many songs use only vocables, syllabic utterances with no lexical meaning.