In music, intonation was a musician's realization of pitch accuracy, or the pitch accuracy of a musical instrument.
Barak-Kadan was a particular favorite of Worf, who valued his traditional approach to opera and his strength of voice and intonation, and noted that there were "none like him." Jadzia Dax, however, found him boring because he never varied his performance "by even a half-tone". (DS9: "Looking for par'Mach in All the Wrong Places")