melodious◼◼◼(having a pleasant melody) adjective [UK: mɪ.ˈləʊ.dɪəs] [US: mɪˈlo.ʊ.dɪəs]The song of this bird is very melodious. = Le chant de cet oiseau est très mélodieux.
sweet [sweeter, sweetest]◼◼◻(having a pleasant sound) adjective [UK: swiːt] [US: ˈswiːt]
mellifluous [mellifluouser, mellifluousest]◼◼◻(sweet and smooth (tone, voice...)) adjective [UK: me.ˈlɪ.flʊəs] [US: me.ˈlɪ.flʊəs]He has a mellifluous voice. = Il a une voix mélodieuse.
harmonic◼◻◻(pleasant to hear) adjective [UK: hɑː.ˈmɒ.nɪk] [US: harˈmɑː.nɪk]