From Longman Dictionary of Contemporary Englishdulcetdul‧cet /ˈdʌlsɪt/ adjective → somebody’s dulcet tones
Examples from the Corpus
dulcet• All pluck and pomp, it rang throughout the hall in dulcet tones as never before.Origin dulcet (1400-1500) Old French doucet, from douz “sweet” 