The student will sing a varied repertoire of songs, with emphasis on diatonic melodies.
It seems that the dulcimer has been taken now beyond its limitations, beyond its diatonic scale.
The plain chant is necessarily a diatonic unison melody.
British Dictionary definitions for diatonic
of, relating to, or based upon any scale of five tones and two semitones produced by playing the white keys of a keyboard instrument, esp the natural major or minor scales forming the basis of the key system in Western music Compare chromatic (sense 2)
not involving the sharpening or flattening of the notes of the major or minor scale nor the use of such notes as modified by accidentals