Croon

потпевну́вање

potpevnúvanje

(soft, low-pitched sound; soft or sentimental hum, song, or tune)

по́тпевне

pótpevne

((transitive, intransitive) to hum or sing (a song or tune) softly in a low pitch or in a sentimental manner; to sing (a popular song) in a low, mellow voice)

по́тшепне

pótšepne

((transitive, intransitive) to speak (words) softly in a low pitch or in a sentimental manner — see also coo)